His instinct is to shut this down before he thinks any more about experimenting with his sister’s powers. And he probably should. The unknown risk to her, to all of them, could be catastrophic. At the same time… His mind still isn’t in the right place after having to bounce around this much, and his emotions don’t know where to settle. His duty is to his family. That’s why he’s even bothered to work with these people, to help find them. To fix this. Vanya is trusting him not to steer her in the wrong direction.

Would she want this kind of help? She already spoke to him about how she almost missed the pills, so it could be a fear based decision. All he can do right now is gather information and give his opinion when they talk.

“You’re not giving her a tattoo.” Let him draw that line in the sand. He straightens up slightly, sounding more forceful with his next questions. “Has it ever gone wrong? What happens to her when it cuts off?”