A/N: I've always loved James & Sirius's brotherly relationship and this idea came to me, I'm not sure how long it'll be, it might only be a three/four parter, or I may continue it after that, depends how attached I become to it:)
It was surprisingly wet for a July night when Sirius Black got off a bus in the middle of nowhere, there was no bus stop around and had anyone seen Sirius appear suddenly they might have been under the impression that he had arrived by magic. There was no one around though, and he tugged on the handle of a huge brown trunk silently, pulling it with some difficulty towards the only building visible for miles. He rapped hard on the door of a large house, hoping that there would be someone home. The door opened, although there appeared to be no one there, he stepped inside out of the rain and shut it behind him. Normally he would never have walked into a house uninvited, but Sirius knew this house well. He also knew that there was only one person who lived there that was too lazy to actually get up and answer the door.
"Prongs?" He called out, his best friend stuck his head out from a nearby room.
"Padfoot!" James Potter jumped to his feet on the sight of his closest companion and partner in crime. He gave him a brief hug before pulling away with a look of distaste on his face. "You're soaked."
"Yeah, I didn't have much time to worry about finding a cloak and the Knight Bus just dumped me at the end of the path, but I was waiting in the rain for it ages…"
"Knight Bus? This isn't an off the cuff visit then? I'm offended, Padfoot, I thought you were just here to see your very best friend." He grinned, but it faded when he saw Sirius didn't return it, but merely shifted his gaze to the doorway, where a his trunk lay, it was emblazoned with a large crest, James knew it was their school crest. That was Sirius' school trunk, and as he registered the look on his friend's face, he suspected that the majority of his worldly belongings were in it. "Have you…you actually…left?"
Sympathy had never been James' strong point, and Sirius knew that this was probably as close as he'd get. He nodded bitterly. "I need to stay, just the night, I'll think of somethin' after that, pester Andromeda or something…."
"You think my mum'll chuck you out? Oh no mate, she won't let you go now you're here."
Right on cue Mrs Potter walked down the stairs, she smiled when she saw Sirius. "James, you appear to have cloned yourself again." She smiled at her young son, almost everyone who met the two boys mistook them for brothers, they were very similar in appearance and inseparable from September until July, parting only for the summer holidays, although that was always reluctantly.
"Is what, dear? In our hallway? I'd noticed." She turned to the second boy, whom she regarded as a second son, with a kind smile on her face. "This is a nice surprise." She embraced him and then, over his shoulder, spotted his trunk. "I know you were coming before school started but it's still July, you've got another month to go, I never expected you of all people to be that keen to get back!"
"He's not here because of school, Mum." Mrs Potter's face hardened and she patted Sirius' cheek affectionately.
"What have your parents done now?" Normally if a teenage boy ran away from home, arriving on their friend's doorstep late in the evening, the adult occupants of the house would expect for the teenager to have done something wrong, however, Mrs Potter knew all about Sirius' family, and all her sympathies lay with the sixteen year old who stood before her, trying to keep face, trying to hide his hurt at five years of family rejection.
"He's left Mum. And he's not going back, he's staying here and if you don't want him to then I can move out with him because we can't make him go back, he's too good for them."
"James Potter! I wouldn't even think of turning Sirius out and you know it! Your father will have something to say when he gets home, I'm sure." She turned to Sirius. "He'll want to pay your parents a visit." Sirius just shrugged. If William Potter wanted to go see the Black family then he knew nothing he said would stop him, he just hoped they wouldn't ask him to join him. "Don't let it upset you, you're welcome here, you're always welcome here."
"I'm not upset, they're pureblood maniacs, they disgust me." He said, with loathing in his eyes that seemed far too old for him.
"You're a good boy, Sirius, now go on, take your stuff upstairs, pick a bedroom, then Jimmy can help you turn it into something fit for a teenage boy, cover it in pictures of half naked muggles, that's all he seems to do these days."
"Mum!" A pink tinge had appeared in James' cheeks, he despised being called Jimmy, it made him sound about six. He grabbed Sirius' trunk and began to lug it up the stairs. "We'll send an owl to Monny and Wormtail, they'll probably be round first thing." He told his friend with a smile.
"Great, they can help me put up pictures of half naked muggles, can't they Jimmy?" He smirked and James removed his shoe, which quickly came in contact with Sirius' head.
"Now, now Jimmy, I'll tell Mummy."
"PADFOOT!" Sirius jumped the banister and quickly ran up the stairs, walking into the bedroom next to James' he shut the door and slumped down beside it, laughing heartily as James attempted to force the door open. "Padfoot, I've got your trunk, I'll steal your Chudley Cannons underwear and show it to the whole school!"
Sirius rolled away from the door, still laughing, and James kicked it open, he pulled Sirius' trunk in and promptly collapsed on top of it, imagining the look on Professor McGonagall's face if he announced the start of their sixth year at Hogwarts by hanging Sirius' boxer shorts out of the astronomy tower.