Thor wants to swear because of course Tony's going to expose more and more of himself. He's certain that Tony's getting off on not getting him off and in some strange way, Thor finds himself getting off on that.

When Tony lifts his hand so the tips of his fingers are nearly brushing against his skin, it takes considerable self-control for him not to reach out and run his hands all over Tony's body, to press his mouth against his mouth, to run his run his tongue along the length of his cock. But when Tony drops his hand, Thor stubbornly lets it rest where it falls.

"Is this fun for you?" he asks breathily. "Watching me suffer?"