Sirius hadn't slept much the night before. He knew it would've been polite to let James know he was on his way, but he didn't have an owl yet and his internet thing was broken. James'd be expecting him, though, Sirius figured. He couldn't stay away for long.
It had been weeks since he'd seen Prongs properly, with him and Lily being in hiding. Part of him didn't even believe that James would be on the other side of the door he was about to knock on. Some stranger would open the door and he would realize that it was impossible to actually find the address written on the piece of paper he had. Well, there was one way to find out. He knocked on the door.