He's just going to watch, folding one arm over his chest and resting his other elbow in his hand in order to just... cup a cheek and watch this weird bio-mechanical being working on himself in a possibly kind of condescending way.

It is a little condescending. He's the devil, what do you expect?

"You've got a convenient little check-engine light? Neat. Bet humans wish they could have one." He's just going to let the guy work on himself though. If he doesn't want someone with medical experience helping, there was no use in offering his own help. Instead, he was going to have a good time watching, whether the strange guy liked it or not.

"Man, those fingers don't look like they're easy to work with. The androids definitely got a better deal. Least you got a nice butt though."