"This is my room and that is my gin." Seth points this out even though they both know perfectly well there's nothing he could effectively do to stop her from keeping it out of reach. Apparently the reminder that these things are his is enough for him, though, because he leans back in his chair and is lightly amused by the wriggling of her fingers.
"This," he says, holding up his bandaged hand, "Is what happens when your brother is an overdramatic idiot."
The fact that Seth just described himself isn't as lost on him as someone (Jonah) might think, because Seth is capable of lacerating himself as well as anyone else when the mood strikes him. The thing about biting at himself is that there isn't anything in it for him. It's unproductive and goes nowhere, accomplishes nothing, and he will never get the reactions he wants to see out of directing his energy inwards. That might be changing slowly, but it's slow enough that tonight he doesn't see the point in dwelling on the places he could flay himself back down to bone.
"Jonah didn't want us to look the same anymore," Seth explains, with the gleaming rationality that belongs to the edges of sanity, the place where things begin to slip in ways that threaten never to recover, "I corrected the problem. If he thinks cutting himself into smaller pieces is going to change that we're the same--it won't."