Part of Foster's lag is based in the fact that both fae and vampires are beings native to Foster's home world. And until... um, very, very recently, he didn't really consider that these fae and vampires might be different--cosmetically, functionally, magically.

This mistake is part of how Foster found himself a vampire himself; by his own rules, he was (or should have been) immune to a majority of their magical powers. Like hypnotic mind control.

Or being turned.

This mistake cost him dearly. So now he's reassessing--or rather, deeply questioning--his entire reality yet again, and it's... not a fun question to ask.

Again.

Strange, however, snaps him right out of it.

"I beg to differ!" It comes out much more... formal... than his usual word choice--but his tone is every bit as disgusted as Strange's gross assumption deserves. He may have a bad habit of echoing speech patterns, but nothing can quash his eagerness to take pointless risks.

"It's not very hard at all. I don't understand why you'd care what I want. You should feel free to do whatever you want to me!"