Definitely revenge, the kind of revenge that is all to delightful to dish out and having Ignis' legs wrapped around his shoulders only encourages him to push further. The sounds he makes, the perfect body spread out above him. Gladio curses under his breath, shifting slightly, pushing up on his elbows a little more and doing two things simultaneously.

The change in angle lets him finally put his mouth on Ignis' cock, swallowing him down in a swift, sudden motion. The whole point is for it to be overwhelming and one more explosive burst of sensation even as one finger, slick with the mess of saliva in his wake presses firmly against the other man's entrance. It's not enough to push inside, not with nothing more than spit, but the promise of it is there, testing and careful. They've never gone that far and Gladio doesn't want to push if Ignis isn't comfortable with it. It's largely impractical given their situation but, just this once, maybe there's time.