There are groans and moans and so much friction. Bodies slick with sweat and hormones crash against each other time and time again, like boats in a rocky ocean, returning home. Sirius does not do this with men yet he knows what he is doing and Remus has not done this with men but he guesses what he should be doing. This isn't the first time, which was tender and tentative and a little boring in its own way, it's the second and they are determined to make it different, better, more passionate, the sort of sex that is zealous and alight with lust. After all, they are a couple of teenagers, each unsure of their own new-found sexualities in a society that quite possibly will not accept them, yet eager to experiment with them.
They are on the cusp of orgasm, and everything begins and ends with each other. The sex is messy and wild but it's the best they have ever had, not that they have a lot to compare it to. Sirius whispers 'Remus' and begins to jerk and shudder, burying his head in his partner's neck but his hand remains firmly between their two bodies. Then James Potter walks in and all hell breaks loose.
James falters for a moment, staring at two of his best mates wanking each other off in what is definitely more than a friendly way, and then turns on his heel with the speed of a Niffler in Gringotts. He throws himself out of the door frame, screaming in a rather effeminate way and turns to run down the staircase back to the safe sanctuary of the common room, where his very straight girlfriend is and his very straight best friend is also. His screaming is attracting a lot of attention and things and not helped when Sirius comes tearing after him, wearing Remus' pants. Sirius shouts for him as he runs down the staircase, causing a hysterical James to twist around and stop mid-shriek, and then to promptly fall down the stairs with an almighty crash.
The next morning, the Hogwarts hospital plays host to Lily Evans, Peter Pettigrew, Sirius Black and Remus Lupin, who are all there to see James Potter, who after a nasty bang to the head, is still unconscious. Madam Pomfrey says that he will be okay, although she can only imagine what he has done to sustain such an injury. Remus and Sirius merely smirk.