Kaldur'ahm (Atlantean Kαλδυρ'αμ) is the former protégé of Aquaman, operating as Aqualad by his king's side and as first leader of the Team. He worked under deep cover as the loyal lieutenant of his father, Black Manta, to bring down the Light and their Partner. Following his extraction from the operation, he was reinstated as leader of the Team.
Aqualad is a very calm person, a trait unshared by the rest of his teammates. Soft-spoken and clear headed, he has a tendency to think things through and formulate plans before taking any sort of action. He tries to see the good in all people, and often acts as the voice of reason amongst his teammates, who were rarely—if ever—as cool-headed as he was. Aqualad always speaks in a formal manner, with an air of respect to all people, both young and old, and he demonstrates the utmost respect to all of the adult heroes of the Justice League, even when he disagrees with them. He holds Aquaman in highest regard because he is his king. Despite his calm behavior, Aqualad was still a teenager, and could at times behave rashly and impulsively. This was, of course, what led to the Team's first mission together.
Aqualad was (eventually) considered by all his teammates to be the natural choice for team leader. He considered the position to be temporary, and believed Robin would take command once he was ready. Although he had proven to be a natural leader, Aqualad seemed reluctant to take the job, calling it a heavy burden. Still, he accepted the role, and had done rather well for the most part.
After leaving the Team under the disguise of becoming a traitor who blamed them for the death of Aquagirl, he took on an image of being ruthless and brutal to his enemies, even his "former" allies and friends. The harshness he displayed to his friends was merely to keep his cover as his father's protégé, while in reality, he was working undercover for Nightwing.
Aqualad is an Atlantean with light blond hair cut at the bottom, deep brown skin, pale green eyes, high cheek bones, and a lean build. He possesses black, eel-like tattoos that run across his back and along his arms and glow a bright blue when using his powers.  Aqualad also has webbed hands and feet and possesses a set of gills that allow him to breathe underwater. 
His superhero costume is a skin-tight, full-body, red-and-blue swimsuit that exposes his arms and feet. The costume has a set of small dorsal fins on the back of the calves. His uniform is outfitted with stealth-tech. Pressing the "A" symbol on his buckle changes his shirt to dark gray and his pants to dark blue. Aqualad also carries a waterpack that holds twin Water-Bearers and water.
Off-duty, he usually wore a blue and black jacket with a high collar to hide his gills and tattoos, black pants and black sandals.
After leaving the Team and joining Black Manta, he wore armor similar to that of his father. It had a disc-shaped helmet with two large, daunting red eyes that also allowed him to shoot lasers; there were small tubes that connected from the back of the head to his shoulders. The hands of his suit were webbed; the suit also sported fins on each of his legs. Hidden in his suit were compartments that allowed him to shoot missiles. He has also shaven the bottom half of his head.
Aqualad came from the Atlantean city of Shayeris, where he was raised by Sha'lain'a, a native of that city, and Calvin Durham, a henchman of Black Manta who was genetically altered to infiltrate Atlantis. However, his actual father was Black Manta himself. He completed his education and began mandatory military service at age 12. At 14, he was transferred to the Conservatory of Sorcery in Poseidonis.
One day, the villain Ocean-Master attacked Atlantis, causing Aquaman to battle with him. During the fight, Aquaman was defeated, but was suddenly helped by the combined forces of Kaldur'ahm and Garth. Using a combination of Garth's magic and Kaldur's fighting abilities, the two attacked Ocean-Master. Though they were easily defeated, this allowed Aquaman precious time to recover and defeat Ocean-Master. After the victory, Aquaman offered the boys the opportunity to become his protégés. Although Garth declined the offer and returned to his studies, Kaldur jumped at the chance to serve his king as his sidekick. He became a superhero two years before his tour of the Hall of Justice.
- Main article: Aqualad in July 2010
Aqualad eagerly expected to become a member of the Justice League, alongside Speedy, Robin, and Kid Flash. However, when it became clear that that wasn't happening, he decided to accompany Robin and Kid Flash to investigate Cadmus Labs. There, they discovered the Genomorph project and Superboy, whom they liberated. The four youths stood up to their mentors and declared they were ready to prove themselves as heroes. They formed a covert ops team and were given their own headquarters in Mount Justice by Batman, and were introduced to Miss Martian.
The next day, Aqualad, Kid Flash and Robin set off on an unsanctioned mission to protect CEO Selena Gonzalez from the League of Shadows, but despite their best efforts, Gonzalez still vanished. 
Aqualad, Robin and Kid Flash asked Speedy to join the Team but were rebuffed. The Team grew restless from the lack of missions, but tried to get to know each other better. They fought Mister Twister, eventually defeating him, which renewed their faith in the Team. The Team later went on a camp-out where they shared the stories of how they became heroes.
The Team's first official mission was to investigate the stoppage of Venom production in Santa Prisca. While Robin initially took the lead, the Team eventually agreed Aqualad was their natural leader. The Team was then sent to stop a plutonium robbery. They defeated Psycho-Pirate and Atomic Skull, capturing the former.
- Main article: Aqualad in August 2010
Aqualad, along with the rest of the Team, began taking training sessions with Black Canary. The Team was assigned to guard shipments of the disassembled Amazo. Professor Ivo was able to retrieve and reassemble the robot, but the Team defeated Amazo and captured Ivo.
Artemis joined the Team just before they were assigned a mission by Red Arrow: to protect Serling Roquette from the League of Shadows while she worked on a counter-weapon to the Fog she developed. Following the successful mission, he officially welcomed Artemis to the Team.
The Team took a class in espionage from Captain Atom. When the lecture proved boring, Captain Atom assigned them a cold case mission–to determine whether or not Air Force captain Nathaniel Adams was framed for the murder of his superior during the Vietnam War. The Team was ultimately successful in determining Adams' innocence, despite Aqualad being distracted by thoughts of Tula.
The Team was later sent by Red Tornado to protect the Helmet of Fate following Kent Nelson's disappearance. While the Helmet was kept safe, Kent died defending it. Two days later, Aqualad and the others attended Kent's funeral.
Later, Batman ordered the Team to track Clayface through Gotham City while he worked on a way to defeat him. Still distracted by Tula, Aqualad allowed the Team to engage Clayface against Batman's orders–the Team was soundly defeated, but saved by Batman at the last moment. Batman questioned Aqualad's commitment to surface life. Aqualad returned to Atlantis to resolve his issues with Tula. He was heartbroken to discover she had begun a relationship with his best friend Garth. At the same time Black Manta launched an attack on Atlantis, which Kaldur helped to repel.
- Main article: Aqualad in September 2010
Following his experiences in Atlantis, Aqualad returned to the Cave with renewed determination. Batman sent the Team to Bialya, where they encountered Psimon, who blocked their memories of the prior six months. The arid climate left Aqualad unconscious for most of the mission, but the others rescued him and Miss Martian restored their memories.
Aqualad invited Superboy and Miss Martian to visit Atlantis with him. They met Kaldur's parents, then went to the capital, where they helped thwart Ocean-Master's plot to steal Queen Mera's powers.
Aqualad provided information for Red Arrow, who was on a mission in Taipei. When it became clear he was in over his head, Arrow called in Aqualad for help, and the pair successfully repelled the League of Shadows' attempt to kill Lex Luthor. The mission revealed the possibility of a mole being on the Team, which Aqualad decided to investigate without informing the others.
Aqualad was present in the Cave when Red Inferno and Red Torpedo attacked. He was held captive in a cage of fire until rescued by Artemis. Like the rest of the Team, he was rendered unconscious by Red Tornado, who fled with his "siblings". Following Red Tornado's apparent betrayal, Aqualad discussed his mole intelligence with Batman, but was overheard by Superboy. He and the rest of the Team were furious with Aqualad for withholding information from them. Batman assigned the Team to investigate reports of gorilla attacks in India. Following advice from Captain Marvel, Aqualad was able to reassert his leadership during the mission. After defeating the Brain and freeing his Kobra-Venom-enhanced animal slaves, he was able to explain why he kept the information secret, to the Team's satisfaction.
The Team was then sent to investigate reports of another Kobra-Venom operation in Bwunda. Miss Martian questioned Aqualad over his lingering feelings for Tula. The Team was ambushed and captured by the Brain's gorillas, but eventually freed themselves and helped the gorillas stage a rebellion against their captors.
- Main article: Aqualad in October 2010
The Team was sent to destroy the central control system being used by the Injustice League to attack a number of cities worldwide with giant plants. They successfully destroyed the control plant, but the ensuing battle with the Injustice League led Kaldur to don the Helmet of Fate, and with the arrival of the Justice League, was enough to force their enemies to surrender. Nabu begrudgingly released Kaldur from being Doctor Fate.
Aqualad later led the Team, along with new friend Zatanna, on a mission to find Red Tornado. Aqualad was not convinced the robot had really betrayed them, and was proved right. Together with Red Inferno and Red Torpedo, they were able to destroy Red Volcano and prevent the Yellowstone super-volcano from devastating the planet.
Aqualad and the rest of the Team took part in a telepathic training simulation run by Martian Manhunter. It went wrong when Artemis's "death" caused Miss Martian to take control, causing them to forget it was not real. Leading the Team as Earth's last remaining heroes, Aqualad sacrificed his "life" to let the others escape attack. When the simulation was ended, Aqualad, like the others, was left devastated. The Team was given therapy by Black Canary. Kaldur felt he had failed by acting as a soldier rather than a general, and offered to resign as leader, only to withdraw it upon realizing there was no other suitable candidate.
On Halloween, Aqualad discussed the possibility of a mole on the Team with Batman, Robin, Red Tornado and Red Arrow. Despite doubts from Arrow and Batman, he was confident the Intel was disinformation.
Klarion cast a spell to make all adults disappear, causing widespread pandemonium. In response to this, Aqualad, Kid Flash, and Robin relayed a message to the world imploring the older children to come together to take care of the younger kids. Within the Cave, Aqualad and Kid Flash discussed the severity of the situation and entertained the idea of using the Helmet of Fate. They ultimately decided not to as the situation was not severe enough to call for its employment.
Later on, Billy Batson entered the Cave, surprising the Team, who were cautious of the stranger. After Billy convinced the Team he was Captain Marvel and explaining to them the situation they were in, Aqualad formulated a plan to take advantage of Billy's abilities in order to rejoin the two separate worlds.
Aqualad and the Team attacked Klarion at Roanoke. With his superior magic, Klarion was able to easily handle the Team. Zatanna was forced to don the Helmet of Fate, much to the disapproval of Aqualad. With the combined efforts of the Team, Doctor Fate, and the adults of the parallel dimension, Klarion momentarily submitted to the attacks, allowing Kid Flash to snatch the gem that acted as the catalyst for the spell. He threw it at Doctor Fate, who merged the two separate worlds simultaneously with Zatara. With his plans foiled, Klarion escaped.
Aqualad was present to celebrate Wally's sixteenth birthday. The celebration was cut short when Batman called the Team for a mission to destroy a number of ice fortresses that were causing extreme winter weather.
- Main article: Aqualad in December 2010
Aqualad was pleased when Red Arrow decided to join the Team. They, along with Kid Flash and Artemis, were assigned to track Sportsmaster in New Orleans. They were unsuccessful in capturing Sportsmaster, the case he carried or discovering the villains' plans.
Aqualad and the rest of the Team, now including Rocket, responded to an alert that Cheshire had been spotted. They found they had been lured into a trap, but were nonetheless successful in defeating their enemies and capturing the case that had eluded them previously. Realizing the trap meant there must really be a mole, Superboy, Artemis and Miss Martian revealed their secret links to their enemies to the rest of the Team, and found acceptance. The Team ambushed Lex Luthor, Queen Bee and their allies on Santa Prisca and captured several villains, though Luthor and Bee escaped.
Aqualad and the others returned to the Cave triumphant, but were shocked to find Batman waiting to tell them the mole was Red Arrow. Despite Batman's orders to leave Arrow to the League, Aqualad took Artemis, Superboy and Miss Martian to find Roy, leaving the others to investigate Red Tornado's mysterious shutdown. Aqualad found Red Arrow, who explained how he had been unconsciously programmed to betray them, and that the Justice League was now under Vandal Savage's control. The team infiltrated the Watchtower and freed the League from the Light's control.
The Team reconvened in the hall, just too late to prevent Vandal Savage and Klarion from getting away. As the clock struck midnight, and New Year, Kid Flash and Artemis, Superboy and Miss Martian, and Zatanna and Robin kissed. In response, Rocket gave Aqualad a peck on the cheek.
While in the mission room with Nightwing, Kid Flash, and Artemis, Aqualad received a new mission from Batman. The archaeologist Helena Sandsmark has been abducted from an excavation site near Olympia, Greece. Local authorities were unable to find her, and Wonder Woman requested that the Team investigate the abduction. Although Aqualad noted that Bumblebee and Lagoon Boy were on special assignment, he assembled the Team and dispatched Alpha Squad to Olympia, under the command of Artemis.
Alpha Squad had been unable to prevent Sportsmaster from absconding with a mysterious artifact, but Artemis managed to plant a tracer on Sportsmaster and retrieved a tablet computer belonging to Helena, which was receiving intermittent transmissions from the kidnapped archaeologist. Kaldur noted that there is more to the abduction than simple kidnapping. Nightwing managed to trace the tracer's signal to Siberia, and Aqualad dispatched Alpha Squad under Superboy's command.
Alpha Squad had successfully subdued Sportsmaster and retrieved two artifact fragments. The Team members noted that the fragments fit together, appearing to be a Babylonian statue, and may have sigils inscribed into them. Aqualad agreed, and dispatched Aquagirl to the Metropolitan Museum of Art to further study the fragments.
Aqualad mused that many of their enemies, Cheshire, Sportsmaster, Killer Frost, and Icicle Jr., had united to locate the statue fragments. He concluded that it must be another operation of the Light. Nightwing noticed that the equipment encountered in Siberia came from LexCorp, and Batman informed the Team that Luthor was currently overseeing a mining operation on Santa Prisca.
With the Light's new dig site now revealed, the Team mobilized a mission to the island. They would rendezvous with Aquaman, who was already on-site to investigate the sudden rise of toxic metals in the soil and water.
Alpha Squad, led by Aqualad, fought their way through Bane's henchmen, Manta Troopers, and LexCorp robots. There was no sign of Aquaman, but Batman informed the squad that Aquaman's last transmission originated near Atabey's Shrine. Upon reaching the shrine, the Team encountered Bane. Bane taunted Aqualad, and threw Aquaman's belt buckle at his feet. With combined teamwork, Bane was defeated, and Alpha Squad entered the shrine.
The Team fought its way through the shrine, which Aquagirl indicated was an 8th-century B.C. temple dedicated to Atabey, a water and fertility goddess, and eventually made its way underground to find Aquaman, held captive in a force field by Black Manta and Lex Luthor.
Manta and Luthor attempted to escape with the third statue fragment on the Manta-Flyer, but the squad managed to disable it by overloading its generators. Manta fought the Team to allow Luthor to escape in a hovercraft, but was defeated. Before he lost consciousness, he despaired at Aqualad's blind loyalty towards Aquaman, and challenged the Sea King to reveal the secret he kept from Kaldur for years. Aquaman deflected the challenge, telling the Team to pursue Luthor. Aqualad agreed, albeit with slight hesitation and much to Manta's disappointment.
Alpha Squad and Aquaman caught up to Luthor's hovercraft, but were unable to apprehend him. However, he left the statue fragment behind when trying to escape. With their enemies defeated, Aqualad returned Aquaman's belt buckle, but told him they had things to discuss.
Back at the Cave, Aquaman and Aqualad had a heated discussion about Aquaman's secret. Orin suggested that Kaldur talk to his parents, but Kaldur insisted on talking with him. The king finally admitted that Calvin Durham was not Kaldur's biological father. He kept it from Aqualad because he did not want him to seek out his birth father. Kaldur pressed Aquaman on his true identity, but the truth was written on Orin's face—Black Manta was his father. Disgusted, Kaldur walked away from Orin and ignored his entreaties.
Aqualad rejoined the others, who had learned more details about the statue fragments. Tula's research indicated that it is from the 2nd Millennium BCE, and was engraved with ancient Babylonian cuneiform, and what Nightwing recognizes as something similar to a circuit board. The statue was of Tiamat, a creature of chaos from the myth of Tiamat and Marduk, an ancient Mesopotamian tale which told of the demigod Marduk who defeated the Chaos god Tiamat with lightning and rain.
Nightwing's repair program pieced together garbled transmissions received during the Santa Priscan mission, and the Team discovered that all the fragments had been located. Helena was worried that her captors would eliminate her since she is of no further use. She overheard her captors mention Gotham City. Alpha Squad, led by Nightwing, set off to investigate Gotham's docks.
Alpha Squad had rescued Helena Sandsmark and captured the final fragment. On further study, Helena realized the new fragment was fake, while Tula had gone missing. Reviewing surveillance footage, the Team discovered that Klarion, who had the real final fragment, had stolen the fragments and Aquagirl had pursued him through his portal to parts unknown. The footage also revealed Tula had found out that Tiamat was in fact an alien weapon.
Aqualad led Alpha Squad, who fought their way to Marduk's temple. Finding the path forward spilt, Kaldur called in Nightwing and Beta Squad to save time. Deep in the temple, Alpha encountered Teekl. Kaldur, attacked the cat, retrieving the Tablet of Destiny it carried. Klarion then arrived with Blockbuster. Kaldur soon realized the tablet was key to defeating Tiamat. Alpha fought and defeated Blockbuster, and Klarion's attempt to take back the tablet resulted in its destruction. With his prize gone, Klarion left, leaving Aqualad dismayed at the loss of their only weapon against Tiamat.
Meanwhile, Beta found Tula and a reawakened Tiamat. Beta was able to defeat Tiamat's various incarnations and free Aquagirl, who sacrificed her life to render Tiamat dormant once more. Aqualad and Tempest arrived soon after, and freed Tula's body from the rubble.
Aqualad left a message for Nightwing, passing on the mantle of leadership to him, telling him that he had many questions and he did not know where the answers would take him. He admonished Nightwing to spend time with the ones he loved.Aqualad eventually parlayed his grief into a mission to infiltrate The Light by working for his father, in hopes of learning more about their plans and their new Partner. This deep cover was done in absolute secrecy  Aquaman was not informed.
Kaldur arrived at the island base, and informed his father that the last of the Kroloteans had been evacuated. He then proceeded to phase two.
While performing a security check, Kaldur noticed the lack of response from Sector 3 guards (who had been Knocked out by Batman). Announcing to the Manta Troopers that the base had been infiltrated, he blasted the water with his helmet laser to eliminate the undersea infiltrators, narrowly missing Aquaman and Lagoon Boy. The fight was on, with the heroes facing against the manta men and Kroloteans.
During the melee, a mysterious figure calling himself "Partner" planted an alien bomb underneath the base, and informed Kaldur that he had five minutes to evacuate his men. Kaldur called for a strategic retreat, but failed to stop Aquaman from knocking off his Black Manta mask. Kaldur revealed himself to his former mentor and friends, who were all in shock. Aquaman in particular hadn't wanted to believe Nightwing when he informed them of Kaldur's defection.
Kaldur spat hateful words at them, blaming them for the death of Tula, and Aquaman for not informing him about his true parentage. Claiming that he now answered to Black Manta, Kaldur launched a shoulder-mounted missile at the assembled group. Superman absorbed the explosion, but Kaldur escaped.
Nightwing and Superboy caught up with Kaldur, who gave them a choice—either they take him prisoner, or they defuse the alien bomb. Superboy attacked him to prevent his escape, but Kaldur subdued him and fled by swimming underwater. He grabbed on to the departing Manta Sub, and left the island before the bomb detonated.
The Manta-Flyer docked with Black Manta's bigger sub, and Kaldur reported the mission results to his father. Black Manta was pleased with his performance, but was disappointed when Kaldur opined that Aquaman was unlikely to have died in the explosion.
In the sea, the Manta-Flyer towed a missile platform into position. Kaldur'ahm and several Manta Troopers left the craft to man the platform and prepared it to target the rocket carrying the Earth-Mars communication satellite.
Lagoon Boy discovered the missile platform and attacked, prompting the Manta Troopers to begin invading the beach. Kaldur'ahm disabled Lagoon Boy, but decided to take him prisoner for the Light's Partner rather than kill him. He then ordered the platform to open fire. When the initial missiles were destroyed by Superboy on the bioship before they could damage the rocket, and Nightwing and Artemis were able to turn the tide against the Manta Troopers, Kaldur'ahm ordered the platform to go to maximum rate of fire and left to take command of the surface forces.
Kaldur'ahm emerged from the water near Nightwing and Artemis and, despite Artemis trying to convince him otherwise, attacked them with a hard-water serpent. The rocket then launched. Kaldur'ahm told his troopers the mission could still succeed and shot a small suit-mounted missile at the rocket. Artemis destroyed the missile with one of her own. Kaldur then charged at Artemis, knocking Nightwing aside. He disarmed Artemis and apparently stabbed her in the chest with a water sword, but actually made the blade curve around her body. As Artemis pretended to fall dead, Kaldur'ahm ordered his men to move out, calling the mission a failure. The rocket then exploded, to Kaldur'ahm's surprise, and he and his men withdrew into the water.
In the Manta-Sub's docking bay, Kaldur'ahm disembarked the Manta-Flyer and was greeted by Black Manta, who congratulated him for capturing Lagoon Boy, killing Artemis, and destroying the satellite. Kaldur'ahm admitted that his team was not responsible for the satellite's destruction, and his father explained that the mission was a test to see if he would take credit for a victory that was not his, having arranged for a bomb to be smuggled aboard days earlier. Kaldur'ahm had passed and was deemed ready for the next level.
Kaldur'ahm arrived at a warehouse to find Nightwing waiting for him, and was soon followed by Wally and Artemis. They discussed the success of their plan to fake Artemis's death, and Nightwing confirmed no-one else knew about it or the fact Kaldur was working undercover for them. Nightwing gave Artemis a Glamour Charm to change her appearance to everyone except the four present. She and Kaldur then went out to a pier and boarded the Manta-Flyer. They devised a part for her: she was to go under cover as Tigress, his new right hand.
In the brig of the Manta-Sub, Kaldur'ahm confronted Lagoon Boy, who was angry about Kaldur's betrayal. At Black Manta's orders, he was to be moved, but Manta denied his son the opportunity to do it himself, as he has another mission for him. Kaldur instead injected a sedative in Lagoon Boy, that also contained a tracer. Manta's mission for Kaldur was one to solidify his trust with his masters in the Light. His mission was to capture Blue Beetle.
Kaldur had a strike team ready, consisting of Tigress, Icicle Jr. and the Terror Twins. They left in the Manta-Flyer, headed for El Paso. Kaldur had to straighten his crew out, as they did not have their minds on the mission.
Kaldur's strike team attacked Blue Beetle and Impulse as the two were in the mountains outside of El Paso. Kaldur kept out of the fight, observing from a ledge. After Beetle and Impulse defeated the strike team, Impulse confronted Kaldur, taking an alien tracking device Kaldur had used to track Blue Beetle. He and Beetle escaped and Kaldur did not pursue.
Aboard the Manta-Flyer, he revealed to his team that he had another device that could track the one Impulse took. That device was meant to be taken, and it would act as a Trojan horse disabling Cave security at Mount Justice.
Kaldur slipped into Mount Justice through the hangar and was met by Sphere, who rolled back after Aqualad touched her. He let his teammates take out all heroes, but he forbade them to kill anyone.
Tommy and Icicle defeated Superboy and knocked him unconscious. They moved on to the Mission Room, where Tigress and Tuppence Terror had subdued Nightwing and Impulse. Blue Beetle was ready to engage in battle but Kaldur persuaded him not to by bringing in a bomb, similar to the one that destroyed Malina Island, and saying it would go off if his finger was removed from a dead man's switch. A collar was placed on Beetle, but before the strike team left, Kaldur confronted Nightwing, punched him in the gut and warned him not to follow. Unbeknownst to the strike team, Kaldur had slipped a flash drive to Nightwing when he punched him.
On the beach, Beetle suddenly attacked after the Scarab had disabled his inhibitor collar and taken control, causing Kaldur to drop the switch and revealing he was bluffing. Beetle charged Kaldur, who hit Beetle at point blank range with a blast of magic, allowing Tigress to shoot a sedative dart that caused Beetle to pass out. On board the Manta-Flyer, Tommy and Icicle Jr. questioned Kaldur's resolve, which prompted Kaldur to order Tigress to detonate the bomb.
Upon returning to the Manta-Sub, Black Manta requested Kaldur accompany him. He took Kaldur to his private quarters, where the members of The Light appeared on video screens. Manta introduced Kaldur, after which Ra's al Ghul officially welcomed Kaldur into the Light and told him he would soon meet the Partner.
Kaldur met with the Partner, and learned it was the Reach. The ambassador gave Kaldur a tour of the Reach's ship, explaining their research and introducing him to the scientist. Kaldur learned that the Reach was studying the Meta-Gene, that Lagoon Boy was in one lab as one of several subjects in which they were trying to stimulate dormant powers within, and that Beast Boy and Impulse were in another lab, being studied to see how those with active Meta-Genes reacted to stress. As the scientist entered a third lab, Kaldur inquired if Blue Beetle was being held there, to which the ambassador told him that Beetle was of the Reach and what they were doing was not Kaldur's concern. Kaldur assured the ambassador that more test subjects were on their way.
When members of the Team infiltrated the Reach ship, Kaldur encountered M'gann, who attacked Kaldur telepathically, causing him to scream and fall to his knees. As this happened, M'gann learned the truth about Kaldur working in deep cover, but her attack left him in a catatonic state. Tigress arrived on the scene and, after a brief confrontation, Tigress threw a smoke bomb and disappeared with Kaldur.
Psimon was about to begin repairing Kaldur's mind, but Tigress, who Black Manta asked to stay with Psimon and Kaldur, secretly took him out with a drugged dart. When Manta returned, Tigress suggested that Miss Martian may have placed a telepathic virus in Kaldur's mind, and recommended that they capture Miss Martian and force her to restore Kaldur's mind. Manta agreed, but insisted that Deathstroke accompany Tigress to ensure her safety.
Miss Martian was captured and brought to the Sub. Black Manta restrained her with a collar, and ordered her to fix Kaldur's mind or die. Her telepathic ability was selectively activated to do this. Communicating telepathically, M'gann told Tigress her intrusion in Kaldur's mind might be considered a threat, so Tigress told M'gann to bring her in as well.
- Kaldur's damaged mind was represented by Atlantis in ruins. M'gann and Artemis were attacked by a wraith appearing as Tula. M'gann warned Artemis to remember that nothing in the mindscape was real, but her overwhelming guilt let her fall victim to phantom Tula's attacks. Unable to help, Artemis sought out Aqualad himself. She ultimately found him, but his facial features were missing. Speaking in Atlantean, Aqualad muttered that all was lost, but Artemis brought him back from the brink. Now restored, Aqualad was brought to M'gann's side. M'gann apologized, and worked with him to piece his mind back together.
When Manta returned to check on Miss Martian's progress, he accused her of stalling, but noticed she had made progress when Kaldur called out to his father.
Aboard the Manta-Sub, M'gann had successfully restored Kaldur's mind but, unknown to Black Manta and Deathstroke, Kaldur was playing possum so he and Artemis could figure out how to save M'gann's life. Manta entered Kaldur's quarters, telling Miss Martian his patience had run out and she had 24 hours to cure his son or die, forcing Kaldur and Artemis to put a plan into action to help M'gann. M'gann didn't want the two blowing their cover but Kaldur telepathically told her he wouldn't allow her life to be risked.
Tigress told Deathstroke she needed to stretch her legs and get coffee, leaving the room so she could head to the control room to deactivate M'gann's collar. Cheshire suddenly entered the room through a ventilation shaft, knocking out a Manta trooper who was subbing for Tigress. M'gann then blocked Cheshire's attempted attack on Kaldur. Cheshire took down Manta troopers who tried to intervene and destroyed the door's controls with her sword. She and M'gann tussled over a trooper's laser blaster, leading to the camera from which Deathstroke was watching being shot. M'gann tried to explain things to Cheshire but she knocked M'gann down. Kaldur then rose and explained to Cheshire that Artemis was not really dead and was, in fact, on board the ship. Not believing Kaldur, Cheshire grabbed him in a choke hold.
Black Manta ultimately intervened, blasting the door open before his troopers could open it with an explosive. He found Kaldur lodged under the door but was attacked by Cheshire and struck with an electrocuting disc. Cheshire was about to move in on Kaldur, but a revived M'gann, whose inhibitor collar had been deactivated, intervened.
M'gann took Aqualad, Artemis, Cheshire and Sportsmaster—who had joined Cheshire in sneaking aboard the Manta-Sub—into a mindscape of Artemis's room. She then revealed to Cheshire and Sportsmaster that Aqualad was working in deep cover, that Artemis's death had been faked and she was posing as Tigress. Feeling her sister's mental presence, Cheshire dropped her grudge against Aqualad, who thanked her for keeping his and Artemis's ruse going.
Released from the mindscape, Miss Martian allowed Cheshire to flee and declared she wanted revenge on Black Manta. Kaldur then tackled Miss Martian to prevent her attack, but Miss Martian escaped by phasing out of the room, as Black Manta embraced his son.
Black Manta presented Kaldur before Vandal Savage and the Reach ambassador, telling them Kaldur's mind was restored and that the shock of seeing his father's life in danger was the catalyst that cured him.
Kaldur was put in charge of security for a summit between the Light and the Reach. When he tried to speak up, Black Beetle ordered his silence but Vandal Savage said Kaldur could speak, given nobody had sacrificed more for the Light and the Reach than he did. Kaldur responded to the Ambassador's question about allowing the Team to access the Bialyan temple, saying that if the Light had known the Reach had sent the Scarab to earth in ancient times, the Light might have made the connection to the temple and guarded it better, a point to which the Scientist agreed, but she was cut off by the Ambassador.
After words turned to blows between the Light and the Reach, Kaldur intervened between Black Beetle and Black Manta, reminding everyone they shouldn't allow petty disagreements to come between them, lest they be distracted from their true enemies, the Justice League and their sidekicks. Manta willingly stood down while Beetle grudgingly did so. Kaldur then asked what would happen when the Justice League members on Rimbor returned to Earth, but Savage assured him that some well placed bribes would ensure their conviction.
At that point, Ra's al Ghul approached Tigress and pulled her Glamour Charm, revealing her true identity of Artemis. The Ambassador and Beetle concluded, because Artemis wasn't really dead, that Kaldur was in cahoots with her and duped everyone in the Light, including his father. Ambassador ordered Beetle to kill Kaldur and Artemis but Manta stepped in front of Beetle. Deathstroke then shot both Kaldur and Artemis in the chest, saying the Light took care of its own. As Manta tended to his dying son, Kaldur declared he had already won, then a dead man's switch fell from his hand.
A holographic message from Aqualad played, in which he revealed that the Reach had thought the Light was working for them but had, in fact, been advancing its own agenda. He revealed how the Light had merely lured the Reach to Earth, then sabotaged their plans as a means to become rulers of the galaxy. Both Savage and the Ambassador were angered by this revelation, but when Savage stated that he had possession of the key to the Warworld, Aqualad and Artemis rose to their feet. "Deathstroke" then revealed her true identity as Miss Martian, other Team members arrived and Aqualad lectured Savage on the true meaning of friendship.
When Savage declared the Light had contingency plans and multiple League of Shadows agents showed up, Aqualad noted Savage's biggest weakness was that he continually underestimated the young heroes. Several of the Shadows revealed themselves to be Team members and all engaged in battle, forcing Savage into a retreat as he escaped with Klarion.
Aqualad then confronted his father, who could not believe his son had betrayed him. Aqualad said he was conflicted given his father's noble qualities, but as long as Manta embraced evil, Aqualad would stand against him. Saying his son needed discipline, Manta attacked but Aqualad countered his assault. Manta remarked he would teach Kaldur to be ruthless, and Kaldur's response was to use a two-hit combo with a water mace to knock his father unconscious.
The Team claimed a decisive victory, although Aqualad lamented that Savage and Klarion escaped, as did Black Beetle and the Scientist, and that Queen Bee and Lex Luthor never showed. Nightwing, Kid Flash and Artemis all reassured Aqualad that he had claimed a decisive win and that it had been one of the Team's best nights ever, probably the best since the outing at Cadmus more than five years ago, and that he should enjoy the moment because he earned it. Aqualad glanced back at his father and his expression softened.
Aqualad was congratulated by Aquaman and Red Tornado for his successful deep cover mission as Nightwing turned leadership of the Team back to Kaldur. Aqualad noted Nightwing had been a successful leader in trying times and Nightwing said he wanted that burden off his back. A boom tube suddenly appeared as an unconscious Black Canary, Black Lightning and Captain Marvel fell out of it. The Warworld was then activated and left Earth's orbit.
The Team raided the Reach flagship, with Aqualad, Blue Beetle and Green Beetle reaching the bridge. Blue and Green Beetle subdued the Scientist and the Reach crew members as Aqualad engaged Black Beetle. Although Black Beetle was able to take down Aqualad and destroy Green Beetle's scarab, his attempt to do the same to Blue Beetle failed and Blue Beetle was able to destroy Black Beetle's scarab. Aqualad congratulated Jaime Reyes on his victory, but Jaime alerted Aqualad that he had learned about the Reach's plan to destroy the Earth.
When magnetic field disruptors planted by the Reach threatened the Earth, Aqualad joined 39 other heroes of Earth in a briefing in Metropolis. The heroes would use a computer virus provided by Lex Luthor to safely disable the disruptors. The heroes were paired off with another into twenty squads: one member would run interference against weapons guarding the disruptors, allowing the other to get close enough to plant the virus.
Aqualad was paired off with Lagoon Boy, as Sigma Squad. He offered to distract the Beetle-tech drones, while Lagoon Boy planted the countermeasure. Lagoon Boy commented that only now is Kaldur trusting him. Kaldur disagreed, as he had entrusted La'gaan with his position on the Team when he left it. With Lagoon Boy mollified, the Atlanteans implemented their plan. Aqualad provided cover, while Lagoon Boy forced his way towards the disruptor, easily defusing it.
Aqualad arrived with other Team members in the Bio-Ship as Flash, Kid Flash and Impulse were able to counter a disruptor that had gone chrysallis and thus stabilize Earth's magnetic field, but it came at the cost of Wally West's life. Aqualad and the others grieved the loss of their friend.
As the League members who were on Rimbor returned to Earth, Aqualad and the rest of the Team arrived. He told the Leaguers the crisis had passed, but at a cost.
Aqualad summoned the Team members to the Watchtower Mission Room, where Batman informed them that the Watchtower would serve as the Team's headquarters, because the Team had earned the right to fight side by side with the Justice League. Aqualad then assigned Superboy, Miss Martian and Beast Boy to Alpha Squad to go to Mars to help Green Beetle; Tigress, Bart Allen (who took up the mantle of Kid Flash), Bumblebee and Guardian to Beta Squad to search for evidence of LexCorp bringing out the Reach drink under a different name, and the others to Gamma Squad to investigate Batgirl's lead on Vandal Savage's next move.
Powers and abilities
- Atlantean sorcery: Before becoming Aquaman's sidekick, Aqualad was trained in the mystical arts by Queen Mera. While he was in the top class along with Tula, his skills have fallen somewhat behind those of Tula and Garth due to focusing his studies as a hero, but his water-bearers compensate somewhat.
- Electricity generation: He has the power to generate electricity from the eel tattoos on his arms, which he can channel through water or use as a direct offense against opponents.
- Hydrokinesis: Aqualad is able to manipulate water to serve any number of uses, e.g. water blasts, whips, waves, shields, or water spouts to lift him into the air. He can manipulate water from a nearby source, like fire hydrants, lakes, etc. or his waterpack. His water blasts are capable of slicing through metal and other materials.
- Hard-water constructs: Aqualad has the unique ability to solidify water into a myriad of different weapons for physical attacks. So far he has created swords, maces, sledgehammers, a small shield, and a large eel. This ability, like his hydrokinesis and electricity generation, is powered by his eel tattoos.
- Atlantean attributes: Atlanteans, although Human, have through scientific and sorcerous means developed several abilities which allow them to live comfortably under the sea:
- Underwater breathing: All Atlanteans are capable of surviving the aquatic atmosphere under the sea. Some accomplish this without the presence of visible gills.
- Temperature resilience: Resistant to low temperatures and the effects of freezing, although notably hindered by high temperatures.
- Durability: Dense flesh, although not invulnerable.
- Strength: Ranging from undetected levels to super strength.
- Toxin resistance: Aqualad has a partial immunity to poisons of sea creatures, such as jellyfish toxin.
- Expert hand-to-hand combatant: Aqualad is extremly skilled in combat able to hold his own against Cheshire alone. In 2016, his skills seem to have improved incredibly as he could take down Superboy with no effort.
- Multilingualism: Aqualad can speak Atlantean and English. 
- Water Pack: A black metallic backpack that holds an unspecified amount of water that Aqualad can use. It also holds his Water-Bearers.
- Water-Bearers: Twin hilts that can hold onto water which Aqualad then uses to create his hard-water weapons. They are also used as a type of water gun to shoot water from his water pack and can be used to help manipulate sources of water.
- Stealth-tech: Technology that is integrated into a piece of clothing and can shift the color of that clothing from the original color to a darker color. Aqualad can access it by pressing the "A" belt buckle on his waist, his "blend" color is dark gray/blue and green.
- Black Manta armor: After defecting from the Team, he joined his father and received an armor like Manta's. It has a laser blast in the helmet, and a rocket launcher. Since rejoining the Team he has discarded this armor in favor of his original suit.
- Helmet of Fate: Due to desperation, Aqualad wore the helmet to help the Team survive their fight against the Injustice League. Thanks to Kent Nelson, Nabu freed Aqualad and let him take off the helmet.
- Dehydration: because his natural habitat is underwater, Aqualad is weakened when exposed to high temperatures and dry conditions.
- Main article: Aquaman
Being the King of Atlantis's partner, Aqualad saw Aquaman as a ruler, a mentor and a father figure. Aquaman had known about his true parentage, but hadn't told him. When Nightwing told Aquaman that Kaldur had defected to the Light, at first, he refused to believe it. However, when he met face-to-face with his former apprentice, he was saddened to learn that it had been true.
- Main article: Robin/Nightwing
When the time came for the Team to choose a field leader, Robin initially saw himself as the most appropriate leader of the Team, citing his greater experience despite being the youngest member of the Team. However, Aqualad explained that Robin's experience and his strong working relationship with Batman meant that Robin assumed his teammates could follow his plans without much explanation, whereas the Team really needed a leader who would be clear. Robin instead suggested that Aqualad should be the Team's leader, and Aqualad accepted. Nevertheless, Aqualad claimed that Robin was a natural leader and believed he would one day be ready to take control of the Team.
Kaldur and Nightwing remained on strong terms, and forged, in secret, a plot to infiltrate the Light and to figure out who their new Partner is. They had trust in each other, though they both knew they endangered themselves and others like Artemis. When Aqualad's deep cover mission ended, he returned to the Team, where Nightwing humbly offered to return command of the Team back over to Aqualad. Aqualad thought it was unnecessary, though soon accepted his leadership status back. After Wally's death, Aqulad objected against Nightwing's resignation. Nightwing corrected him and stated that he was only taking a leave of absence, Aqualad understood his wanting to be away from the hero lifestyle for a while and continued to lead the Team.
- Main article: Black Manta
Black Manta is Aqualad's biological father. He was originally unaware of his true parentage, believing himself to be the son of Manta's former henchman, Calvin Durham. As part of his cover, Aqualad pretended to be a loyal son to Manta, and with Nightwing's help, he hoped to cement his father's trust in him to reveal information about the Light and their new Partner.
When Kaldur's mind was damaged by Miss Martian, Black Manta displayed the utmost concern for son, to the extent where he kidnapped Miss Martian and demanded that she repair his son's mind. Their relationship was crippled when the Light discovered Aqulad's true intentions. Initially, Black Manta was shocked and saddened by this revelation, though his feelings towards his son quickly turned sour. Although Aqualad's heroic nature conflicts with Black Manta's villainous attitude, he still sees nobility in his father.
- Main article: Miss Martian
Aqualad was Miss Martian's teammate and an earnest friend. He sometimes helped her with unfamiliar aspects of Earth culture. Miss Martian has mentioned that she looked at Aqualad like an older brother. When Aqualad infiltrated the Light and "killed" Artemis, Miss Martian was saddened by his actions. She soon encountered him on The Reach's ship, where she condemned him as a murderer for his actions and used a mental blast on him. She was shocked to discover that he was really undercover and that Artemis was still alive which left her in a heartbroken state.
- Main article: Garth
Aqualad was best friends with Garth back in Atlantis and they along with Tula trained together at the Conservatory of Sorcery under Queen Mera. When Kaldur'ahm became Aquaman's protégé he left his studies and carried out his responsibilities as Aqualad, and later joined the Team. During this time, Garth and Tula began dating, which hurt Aqualad who also had feelings for Tula. Their friendship was strained but they eventually reconciled.
- Main article: Tula
Tula was Kaldur'ahm's crush, a classmate from the Conservatory of Sorcery. After Kaldur became Aqualad and left for the surface, Tula began seeing Garth. Unaware, Aqualad thought long of Tula, and considered leaving the Team for her. He eventually accepted their relationship.
Tula's death during a mission for the Team took a heavy toll on him, causing him to leave the Team. Aqualad blamed his former teammates for her death, which they believed was one of the reasons he joined the Light.
Kaldur'ahm was developed specifically for Young Justice, rather than using the existing Aqualad, Garth. There were several reasons for this. In the comics, Garth had stopped using the name Aqualad and started going by the name Tempest. Furthermore, Garth had been killed off during the event Blackest Night, so the character was not current at the time of development. A new character also provided an opportunity to add more diversity to the cast. Kaldur'ahm was therefore created, inspired by characters such as Cal Durham, as well as the DC series Arion, in which it was revealed that not all Atlanteans are Caucasian.
During production of the series, Geoff Johns saw the designs for Kaldur'ahm and decided to transfer the character into the mainstream DC Universe as the new Aqualad (replacing Garth). Johns's Aqualad has a slightly different background to Kaldur'ahm: rather than being raised in Atlantis, he was raised as a human in New Mexico and he goes by the name Jackson Hyde rather than Kaldur'ahm. He lacks Kaldur's obvious Atlantean physical traits, but retains Kaldur's eel tattoos and powers (in the TV series, the tattoos were given to Kaldur by the Conservatory of Sorcery; in the comics, Jackson Hyde was born with them). Jackson Hyde first appeared in Brightest Day #4, which preceded the pilot movie of Young Justice by five months. Jackson became an important character in the Brightest Day series, and promotional art revealed that he was intended to become a member of the Teen Titans. However, due to the events of Flashpoint, this did not come to be. He did not appear in the New 52 and finally appeared briefly in Johns's DC Rebirth #1. In a brief scene, it's revealed he is a homosexual teen from Silver City. He has not appeared since.
A version of Kaldur'ahm similar to his appearance in Young Justice appeared in Justice League: The Flashpoint Paradox.
Aqualad's physicality is based on American Olympian swimmer Michael Phelps. His costume combined the aspects of the Aqualad in the comics, as well as the full-body suits used by Olympians in the 2004 Athens and 2008 Beijing Olympics.