Disclaimer: I, of course, don't own Harry Potter, and am just playing with JKR's amazing creations.
A/N: This was inspired by an adorable head-canon I found on tumblr, by a user whose name I don't remember... Sorry...
"Remus," whined Sirius, as he poked his head between the curtains of the four-post bed.
Remus grumbled something unintelligible, turning his head over on the pillow.
"Remus," Sirius repeated, "Moony, Moony."
Remus rolled over, and cracked an eye open at Sirius. "Wha?"
"I'm cold. My feet are cold."
Remus's alarm clock rang, and he was awake as if struck by lightning. He sat up, and rubbed his eyes.
Sirius pounced on him, burrowing under the covers at superhuman speed.
"Pads, your feet are so cold." Remus yawned.
Sirius grabbed onto Remus. "You're so warm," he mumbled. He wrapped his arms and legs around Remus, as Remus tried to get up.
"Geroff, Sirius," grumbled Remus.
Sirius ignored him.
Trying, and failing, to shrug with the weight of a sixteen-year-old Sirius on his shoulders, Remus made his way to the bathroom, through the minefield of James's dirty laundry.
With Sirius still attached to him, Remus put toothpaste on his toothbrush, and attempted to brush his teeth. Somehow he managed to not choke on his toothbrush.
Halfway through brushing his teeth, Remus tried again. "Pads, please let go of me."
"No," came the muffled reply from Sirius.
"How long do you intend to stay there? We have class in twenty minutes, and Mcgonagall will not be pleased to find you hanging off me like a koala." Remus spit some of the toothpaste foam into the sink.
"Koala?" asked Sirius, voice still muffled from where he had buried his face in Remus's shoulder.
"You can't seriously-" Sirius giggled at the pun, and Remus ignored him "-not know what a koala is."
"Yeah," said James, who was finally done looking through the piles of semi-dirty laundry on the dormitory floor, and had just entered the bathroom, "even I know what a koala is."
In the mirror, Remus saw Sirius's puppy-dog eyes, his irresistible puppy-dog eyes.
"Fine," sighed Remus, trying to talk around his toothbrush, "a koala bear is a fluffy, gray animal. It's about the size of a large cat, and spends most of its day asleep. The babies hang onto their mother like you are hanging onto me, and the adults hold onto trees like that as well."
For a moment, Sirius was silent. He looked deep in thought, frowning. Remus continued to brush his teeth.
"You're comparing me to a fluffy little bear thing?" said Sirius finally, just as Peter came through the door. He looked at Sirius, shrugged, deciding that Sirius had said weirder things, and started combing his hair.
"Yes."
"No," Sirius pouted, "I'm tougher than that."
Remus tried to shrug again. "Ok then." He attempted to pry Sirius off of himself. "James, a little help here?"
James grinned, and continue to brush his own teeth. "Nope, this is way too funny."
Remus shook himself, and finally succeeded in getting one of Sirius's arms off himself.
"Noooooooooooo," Sirius wailed loudly.
A/N: I'm not sure if this is mild wolfstar or just marauder-friendship-fluff... take it in whatever way you like.