The moment that Harry wrote that the Dementors had come and that Dobby had rescued him and Dudley by popping them home, Sirius left the house to go and get his godson. He didn't wait to ask Dumbledore. He didn't tell anyone where he was going. He just left. He went straight up to the attic and tried to think of a place to Apparate. He remembered, when he was Padfoot, an alley near where he saw Harry catch the Knight Bus. With that thought in mind, he disappeared.
Sneaking to #4 Privet Dr in the middle of the night was exhilarating. It had been too long that he had been cooped up in Grimmuald Place and it was fun to be out doing something.
He found Harry's house from the number, since all the houses looked alike, and he climbed the medium sized tree in the side yard. Getting up as far up as he could, he looked for the window that looked like it had been barred. Seeing the holes in the walls by the small window on the first floor at towards the back of the house, he rapped on the glass with a stick, hoping he had the right room. He didn't know what he'd do if it was Harry's cousin, or worse his uncle. He breathed a sigh of relief when he saw Harry's unruly hair as the boy stuck his head out of the window.
"Sirius," the boy harshly whispered, looking frantically around, like the Aurors would pop up any moment, "what are you doing here? You could get caught." A worried frown etched his face as he took in the sight of his godfather. The man looked better than Harry had ever seen him. His face had filled out and his hair was clean and healthy looking. He was dressed in robes, which Harry thought was out of place, but they were nice robes, and very upper crust looking.
"I came to spring you from this joint," his godfather replied, taking in his godson's appearance. Harry didn't look good. He had lines on his face as if he had been stressed out for ages. His unruly hair was lank and stringy. His face was gaunt and pale. Sirius was more determined to get the boy out of this house and help him in any way he could. "Get your stuff and we'll leave here. No, wait, have Dobby pack it for you, he can bring it later. Grab only what you value most. It'll be quicker."
Harry ducked back into his room and Sirius waited. Soon enough, the boy reappeared, a satchel on his back. "Dobby, hide and wait for my call," he ordered softly towards his room as he flung one leg over the sill. "If the Dursleys see you, just pop away. I'll call you as soon as I can."
"Come on. Quickly now," the fugitive said quietly, making a come-along motion.
"Alright, hold your horses," Harry said as he straddled the windowsill. He swung his other leg over and braced himself on the sill. Then he jumped to the tree and made his way to Sirius.
"Great job, Harry," the man praised, making Harry blush with pride.
Not many people in Harry's young life had praised him. Mostly Hermione, even she didn't do it often. "What now?" the boy asked, forcing the blush away. He didn't want to come off as immature.
"Down the tree, and to that alley a few blocks down," his godfather said, pointing to the dark alley a few streets away. "We have to get away from your house. Don't want the Aurors showing up when I Disapparate. Come on, quickly now."
The two shimmied down the tree and ran off down the street, going over a few blocks to the secluded alley.
"I'm going to Apparate us to my house. Here read this, and remember it," Sirius said, giving him a piece of paper with the secret. Harry read the note, with light from the streetlamp, and then tried to pocket it, but Sirius shook his head and snatched it away. "I need to hold on to it. If you lose it, anyone can get into my house," he explained, pocketing the slip of paper.
"Oh," the teen said, nodding in understanding, but with a confused look on his face.
"I'll explain later. Hold on tight," Sirius said, holding out his arm for Harry to grab. "Take a deep breath and hold it, it'll make it easier."
Harry took the arm and inhaled deeply, holding it, and nodded his readiness. With a twist, the two were gone. They reappeared again in a dingy room. Harry stumbled a bit and groaned at the turning of his stomach. He shook his head, grabbed his belly and righted his feet. Then he took a good look around. It looked like an attic to Harry. "Where are we?" he asked, noting all the trunks laying around.
"My house. Don't touch anything, it might bite. I've had the house elves put all the Dark stuff up here, until I can get it the DoM," Sirius explained as he headed for the door, Harry following behind. "They were putting them in my room, but this place is riddled with Dark objects, so I made them move it all here. No one is allowed in but family," he added, making Harry puff up at the thought that he was family.
"What's the DoM?" the teen asked, gripping on to his satchel. He straightened up at the thought of Sirius considering him family. It had a nice warm feeling.
"The Department of Mysteries," came the answer. "They research magic stuff, mostly. I think they even have a room dedicated to the 'magic of love'," he added with a shrug.
As Harry walked through the house, he couldn't help but notice how clean it was. The wooden floor shined, and the windows were clear as day, though it was night. The wallpape