Notes: To see the original artwork that inspired this piece, you can read this story at my AO3 [listed in my profile].
Those bloody dreams. They kept plaguing his sleeping mind, and now they were starting to trickle into his consciousness at the most inopportune of times. So one particularly trying afternoon, after having been subjected to numerous hard-ons and full-body flushes, Sirius decided to lock himself in the Gryffindor Boys' bathroom to get rid of these needs.
Undressing was nearly excruciating. He dropped his robes and shucked his shirt and vest off easily enough, but below the waist was another matter entirely. Carefully, both hands undid his flies and he shimmied his hips, his fingers peeling the trousers and pants away from aching flesh that gratefully sprung free. A minute later, without even grabbing a towel or giving a damn where his clothes landed, his hands reached for the tap and set it to blasting. Sirius eagerly stepped in and muffled a yelp at the temperature.
After a few steadying moments, he let himself relax against the wall behind him as the hot water pelted down the front of his body. His left hand ran down the flat expanse of his stomach until it reached its goal, gripping onto the base of his shaft. As he stroked himself, the flesh hardened further beneath his hand and he groaned low in his throat, nearly growling at the combined stimulus of his hand and scalding water.
One arm cushioned his lower back when his hips started to rock of their own accord, the entire length of his erection pumping through the tight ring of his fingers. Images started to flood his mind; replaying his dreams over and over again. The familiar dream face contorted in pleasure had Sirius gasping for air as his fingers tightened and he pumped faster.
Right when he thought he could die right there from the mounting tension in his body, the ache so deep he felt it in his bones, the dream face fell back and its lips formed the tantalising name that had always managed to push Sirius over the edge: 'oh, Padfoot…'
The tingling behind his balls got tighter and sharper until he couldn't hold it and he let himself go, thick ropes of pearly white bursting from him and staining the shower wall obscenely. His body slumped against the wall behind him while he panted for air, squeezed his eyes shut, and pretended that he hadn't just cried out the last name he ever thought he would: Remus.