So 55 seconds into this video interview, watch it- http://youtu.be/Lrs-_kZCIBQ
Didn't watch? Okay so writer of the show is wearing a green shirt that has "Hello, Megan!" written on it in red type. He says that the t-shirt is a spoiler and for those watching the show gives a big clue as to what is up with her.
MY THOUGHTS AS TO WHAT THE HECK THAT MEANS:
1. Megan is the Mole. I mean the number one question floating around Young Justice right now is "Who or what is the mole?" And quite literally his shirt could be giving us the answer. "Hello, Megan!" Also the red color of the writing could mean 'danger', 'stop', 'warning'.
2. Megan is a Red Martian. In Issue 6 of the Young Justice comic Miss Martian talks about being chosen by Martian Manhunter after a big competition on Mars. It also talks about the politics and make up of Mars. There are apparently 3 races. Green, red, and white martians. She talks about how the white martians are treated unfairly but nothing is really mentioned about the green or red ones. In the rest of the DC universe Red Martians are not mentioned. Wikipedia tells me there are 3 races on Mars but instead of red, the third is Yellow. If Young Justice is going through the trouble of making a new race on Mars for what purpose? A new origin story perhaps? Maybe the white martian we see in Bereft is a loved one and not infact HER.
3. Megan is a not the Mole. Since "Who is the mole?" is the biggest question his shirt could just mean that they are about to start hinting around that Megan is the mole and in fact she isn't. That instead she's a red herring meant to throw people off the track.
4. Megan is going to die. The creators made it clear that not everyone was going to survive to the end of the show. The "who is going to die" question is a little ways away but red lettering could be indicitive of blood and like thought #1 be the literal writting on the wall(or shirt) of who is going to bite the big one.
5. Megan is angry/embaressed/in love. A simple expression of the color red but I doubt any of these count as big enough to be considered "a spoiler on what is up with Miss Martian".
6. It means nothing or something else. 'Cause who knows!?