At this point, everyone can figure out that the Thomas and Aris are speaking in their heads because they're looking at each other with strange googly-eyes.
Aris tells the kids that WICKED made some girl named Beth stab his best friend, Rachel.
So Beth was the female equivalent of Gally, while Rachel was the female equivalent of... oh, boy—sounds like she was supposed to be the equivalent to Thomas.
Remember, Rachel is to Aris as Thomas is to Teresa. Therefore, Thomas should be dead.
Then Aris calls everyone sticks. Looks like Group B made up a vocabulary, too, just as Group A did. Group A calls everyone shanks.
A random Glader points out a black splotch on Aris's neck. Everyone stand back.
It's a tattoo. It says: "Property of WICKED. Group B, Subject B1. The Partner" (6.27).
Everyone's pretty amazed at this, and soon they realize that they all have tattoos.
Minho's says "The Leader," and Newt's says "The Glue." Most of the random kids don't have labels, though—just markers like A2, A3, A4, and so on.
Then Thomas asks Newt what his says, and Newt looks a bit scared to tell him.
After a bit of hesitation, Newt gives in. Thomas's says "To be killed by Group B" (6.62).