Steve exhales hard through his nose when Zerxus' hands tighten and tenses up against them. Not to get away or discomfort but more just a wave of... wanting more of it.

He uses the hand without the needle and swats Zerxus' gently on the forearm.

"Stop that. I don't need to untangle why a half-dead demon covered in blood in hell is turning me on." Well. At some point... Steve often breaks to uncomfortable honesty and truth. "What you did was stupid, but I'm not gonna argue with it - but only on the grounds that you got to make a decision for yourself and that probably was worth it."

It does not make him feel less like it was his fault, here. Leverage. Almost immediately. He hates it. He also can't do anything about it.