Watching Fives touch himself - easy and attentive and exploratory - is. Difficult. Even though he knows it must be disturbing, to have so many scars and his tattoos gone, even though it's a perfectly reasonable reaction for Fives to have. It's just. An image.

Getting his dick out for something as routine as relieving himself is relatively easier to deal with.

"Technically, right now you are exactly as big as me. You're the only body I've got, so that's how big I am." If he's going to be a smartass, he might as well get his money's worth.