A/N: In the end I realized Sirius runs away when he's 16, so they act quite young, but I decided not to change it.
Around midnight, James suddenly woke up. He lay in his bed for a few seconds, wondering what could have woken him, when he heard it again. Someone was knocking on the front door. He got out of his bed and went to his parents' room.
"Dad? Someone's knocking on the front door… Dad?"
Tom Potter turned around, only half woken. "You sure? You're not dreaming?" he said sleepily.
"Yes, I'm sure," said James, at the same moment they heard the knocking again.
His father got up. "Let's go have a look," he said, while putting on his gown.
They went down the stairs, James right on his father's heels. James's father was holding his wand in front of him like a sword.
When they reached the front door, his father gestured James to step back. "Who's there?" he asked through the closed door. No one answered. He glared at his only son.
"I'm sure I heard someone knocking!" James said defensively.
His father turned to the door again and opened it. The only thing he could see in the dark was a trunk on the front steps of their door. James was peering under his father's arm to see as well. Mr. Potter looked at it for a couple of seconds and then stepped out the front door to have a closer look, his wand still raised. As James watched his father inspecting the trunk from every side, he suddenly got scared. What was it doing here in the middle of the night?
Suddenly, his father let out a gasp. "What are you doing here?" he asked the back of the trunk. Apparently, someone was sitting against the backside of it, since the trunk was able to answer his question.
"I'm sorry to wake you, sir," answered the mysterious person sitting behind the trunk, "but I didn't know where to go except for this place…"
James recognized the voice at once. "Sirius?" he shouted towards the trunk. At the sound of James's voice, Sirius's head peered around the trunk. "Hi Prongs," he said. For the first time ever he wasn't grinning while he said that. He rather looked like shaken.
"What are you doing here?" James asked his best friend.
Sirius opened his mouth to answer, but James's father cut him off. "Let's first get you inside. It's a quarter past midnight and we're all freezing."
He grabbed Sirius by his upper arm and pulled him on his feet. Then he took Sirius's trunk and dragged it inside the house. James moved aside in the door post. As Sirius walked past him, he noticed how sad and lean his usually cheerful friend looked.
"Sit down," James's father said, gesturing towards an armchair. He pointed his wand at the fireplace and at the moment the fire started burning Mrs. Potter came down the stairs.
"What is all this fuss about?" she asked. "Sirius? What are you doing here?"
"Yeah, that's what I've been asking you all the time," said James, hanging over the back of Sirius's armchair.
"I - I ran away," Sirius answered, looking at the carpet. "I couldn't stand them anymore. And out there, in the dark street, I could only think of one place to go…"
He suddenly looked directly at James's mother. "Could I please just stay here for tonight, Mrs. Potter? Tomorrow I'll be going to my uncle, over in Scotland. He's the only one in my family who's on my side."
"Of course you can stay here, Sirius," James's mother answered. "You can stay even longer than just one night if you want to."
Sirius looked at her gratefully.
"You can take James's room. James doesn't mind sleeping on the couch," said Mr. Potter.
"What?" James roared, turning around to his father, who was grinning at him.
"The couch is fine to me," Sirius said.
"Are you sure?" Mrs. Potter asked him. Sirius nodded. "I'll get you some blankets then." She headed back upstairs.
"So who's this uncle?" James asked Sirius.
Sirius turned around in his chair. "Alphard Black, my mother's brother. He was the only one of my family who sent me a Christmas present last year, besides Regulus."
James remembered very well how little presents Sirius got last year, since he'd been celebrating Christmas at Potter manor. He'd only got two from his family, three from his animagi friends and one from James's parents. James himself had got loads of presents from his family, even from aunts and uncles he hadn't seen for over a year.
James's father interrupted his thoughts. "Does your uncle know you're coming?"
"He doesn't. Not yet. I think I'll be sending him an owl tomorrow..."
"You don't have to," James interrupted him, "why don't you just stay here? We won't mind!"
"You don't mind," Sirius retorted.
"Helen and I don't either," Mr. Potter said.
At that moment, Mrs. Potter came down the stairs, a couple of blankets draped over one arm, clenching two pillows under her other arm.
"I'll prepare the second bedroom tomorrow, for tonight you and James will be sleeping here." She draped the blankets over the two couches next to the fireplace.
"Thank you so very much, Mrs. Potter!"
"No thanks, Sirius. Now, both of you better go to sleep, it's already half past midnight! We're going back to bed as well, come on, Tom." James's parents left the living room.
Few minutes later, Sirius and James were lying in their 'beds'. Sirius was looking at the fireplace. James could tell from his face that he didn't know what to say.
"Padfoot?" James asked hesitatingly. Sirius turned his gaze away from the flames to look at him. "Did they take away your smile before you ran off?"
He didn't really know what to say to his friend, he just knew he had to say anything, no matter what. He had to make Sirius smile again. Only then he would know that his partner in crime was really here, in the middle of the night, without potential brain damage caused by his Slytherin family.
It worked, he did smile. "They didn't. Guess they forgot the unsmiling-jinx. They should've asked Kreacher. I'm sure he still remembers how he lost his ability to laugh."
James smiled. Only Sirius could talk rubbish like that only hours after running away from home.
"My parents have never been jinxed with that spell though," Sirius went on, frowning. "They've been hexed to think, do and see only evil things for the rest of their life. Probably tradition among the Blacks to do that with every newborn child."
"Good thing it didn't work on you," James said. "Otherwise you'd be serious your entire life!"
Sirius grinned at the pun.
"That's probably why they called you Sirius, since the hex failed to make you serious."
Sirius was chuckling now. James was almost there. He'd almost made him laugh.
"We shall rename you. A name that suits you better. How about… Padfoot?"
And at least Sirius was laughing. But only seconds after James joined in, his father came halfway down the stairs, asking them to be quiet now. Still chuckling, they fell asleep.