Muffled thumps against the wall woke Sam with a start, and habit made him reach for the gun under his pillow. A low moan seeped through the wall, deep, so gravelly it skinned his nerves and made him shiver involuntarily. He stilled. He knew that kind of sound. But he hadn't heard it from that voice before.

Sam had never regarded Castiel as a sexual being. He had always quietly assumed without really thinking about it that Castiel didn't have those kinds of desires.

An alarmed, agitated cry drove all remaining doubts out of Sam's head. Castiel was definitely doing something fun next door.

Sam held a pillow over his ear, but if the wall couldn't block the noise, the pillow wasn't going to do much more. Sam angled his watch so it was illuminated by the moonlight slipping through the curtains. 3:00 AM. Of course. He wasn't going to get back to sleep before it got light.

Sam was considering going downstairs and grabbing a drink before another sound reached his ears. It was a groan, deeply male, deeply urgent. But it wasn't Cas.

Sam froze up for a split second. He knew that voice too.

Quickly, Sam wondered if he was hearing wrong and the pair of them were actually in pain, being tortured in the very next room by a pagan god or demon or ghost that had gotten lucky and caught them unawares. But no, that wasn't within the scope of possibility. And a quick, panting crowing of Dean's name in Castiel's normally flat voice made that perfectly clear.

If Cas used to be a virgin, he wasn't anymore. Dean was fucking the innocence right out of him.

Sam squeezed the bridge of his nose and sat up. No way was he getting back to sleep. Unbidden, a panorama of detailed images flashed before his eyes. Castiel, on his knees on the mattress, one hand gripping the headboard. Castiel, flat on his back with his knees lifted and Dean bearing down, beating down, staring down at him. Dean on his back holding Castiel by the thighs as Castiel straddled him, scrunching the blankets in his fists, bouncing erratically. Castiel face down, writhing, bucking, as Dean pounded into him, pushing his angel's thighs further apart.

Sam had guessed in the back of his mind that there might have been something more going on between his brother and Castiel. Castiel had fallen – no, jumped – from heaven in order to support Dean's crusade. Dean had had a powerful corrupting and liberating effect, and at the very least, Sam had always suspected that Castiel was head over heels. He didn't understand how else an angel could become so unconditionally devoted to Dean's philosophy of life, to obediently come whenever Dean called, following along by his ankles like a dog. Castiel had tossed aside his dignity, and more than that, his family, to be loyal to Dean. If that wasn't love, Sam wondered what was. Dean's feelings for Cas had never been a topic for discussion. Aside from the occasional joke (more due to Castiel's frank way of talking about their "profound bond"), what existed between them was never treated as more than an alliance and friendship.

Even when Castiel had returned, battered, but alive, and Dean, stunned for a moment into showing his feelings, had hugged him. The Leviathans had had no use for that body. The angel was where the expansive knowledge was stored, and they couldn't access that, and Jimmy's body was no more than a shell. That having been said, it was a miracle Castiel was alive, and Dean had clearly presumed him dead. Bobby and Sam said nothing about how thrilled Dean was that Castiel had returned to them in one piece. No-one had talked about the look on his face, or the fact that he had kept Castiel's overcoat in the car, or the way he appeared to simply forget or forgive Castiel's dangerous suicide mission in hoovering purgatory, or the way …

But now, Dean was praising Jesus, and Sam wondered if that ruined the mood for Cas or made him hotter. From the responding moan in Castiel's thick, husky voice, Sam guessed that it was the latter.

The thumping slowed and soon ended, but some muffled sounds continued until finally a quiet grunt of satisfaction, which could have come from either angel or human by that point, signalled that they had settled down.

A small part of Sam was glad they'd finally gotten it over with. Another part wanted to tear them a matching set of new holes for waking him up in such an inconsiderate way. They knew he was right next door, dammit.

In a couple of hours, the sun began to rise, and Sam resigned himself to just another night of bad sleep.