Being bitten, even just a little nip, makes him groan and return the favour. Thanks to Crais and his habits, Bashir is likely developing a somewhat Pavlovian response to being bitten.

"That's good to know. I hope never to upset you, but should that happen, I will keep a hand on you and not leave your side unless it's necessary." Having the space to talk about his own boundaries and what he needs has been genuinely very good for Bashir. It's made him markedly more comfortable with sex and his own body. "I should also make sure that you know that I enjoy sex, intimacy, and all that comes with it, but I don't always physically display it. The state of my cock is my own biology and not a reflection on you."