Harry Potter AU where instead if standing there laughing like a lunatic, Sirius transforms into a dog at the last second and gets away from the Ministry. Thus beginning his years as That Stray™ of Privet Drive. Prepare for an insanely long post just fyi:
He shows up about a week after Harry is dropped on the Dursley's doorstep.
Sirius is smart enough to understand he's a wanted man and can't reveal himself, and they would never let him take Harry, so he does his best from a distance.
No one really notices him at first, some people think oh he moved in with these people or those.
It takes them a while to realize he's a Stray.
They try to chase him off but he always comes back, and mysteriously disappears whenever the dog catcher is called.
He lingers mostly by the Dursley's, finding a nice rose bush to burrow under that gives a perfect view of the house.
It's a vigil he keeps up for years, ears perking up whenever he hears a baby crying. He can so easily pick out Harry's cries from that other kid in there, but it pleases him and worries him that Harry doesn't cry that often.
For the longest time he doesn't see Harry. He eats from the trash and sleeps in the rain, occasionally daring to move towards the house and try to look through the window.
The first time he gets a look at Harry is half a year later. He's seated in a worn out highchair looking curious as he plays with bits of cereal laid out for him, while his aunt and uncle stand on the other side of the table with another highchair and another baby.
This one pudgy and red faced and screaming as his mother, Lily's sister, tries to get mashed carrots and peas down his throat. He doesn't settle until Petunia gives him a cake, and sets the baby food in front of Harry without a spoon.
There's a scar on his forehead that Sirius sees for the first time, still red and blotched purple as if still healing, in the shape of a lightning bolt.
Sirius' heart breaks in half as his baby godson eats the food left for him unsupervised, scooping the mush onto his fingers because it was familiar and eating it. He looked happy enough, but Sirius could hear through the window when he swivels around and chatters "mumma? Mumma?"
"It's talking again, Petunia darling."
"How am I supposed to stop it?"
"Shut him up, he's upsetting Dudley!"
Sirius growls, Harry must have heard, his green eyes finding Sirius at the window and breaking into a grin as he waved his fists, "Pa-foo! Pa-foo!"
Sirius wants to cry. Harry remembered him.
Then Petunia sees him and screams, Dudley starts crying and Vernon Dursley yells at the window and crashed to the ground, tripping as he tries to get out of his chair, but Harry is laughing and clapping and Sirius feels pleased with his work as he dashes off to hide.
The first time he's given the chance to get near Harry and not just see him through the windows is when harry is five years old.
It's a scorching day out but Harry is sitting on the front stoop of the Dursley's home. He'd been brought there thirty minutes ago by Petunia and given a popsicle, told to keep quiet while Dudley's having his playdate.
He's dressed sloppily, his clothes are too big for him, his sleeve stained in the popsicle that was melting down his hand because he couldn't eat it fast enough. His eyes were squinted like he couldn't quite see and Sirius could already tell he would need glasses. Why he didn't already have them was a mystery.
Sirius, hiding under a bush till that point, creeps out and over to Harry with his head low, just in case he startles him, but little Harry is so brave even at his young age, head turning to squint at Sirius and lighting up when he seems to realize it was a dog.
The polite boy he was offers his popsicle to Sirius, who wasn't rude enough to refuse, and they spend the afternoon finishing the popsicle before he sits next to Harry, who babbles on and on about everything, though he couldn't quite talk well yet. He was a smart boy, despite being only five years old.
Sirius almost forgets he shouldn't be there when Petunia opens the door hours later and screams in horror. Sirius bolts as Vernon sends a kick at him, and Harry complains about his friend being chased away.
Mrs. Figg is not a dog person, but Sirius IS a cat person, and her cats take a liking to him immediately. Some seem to know he was more than what he appeared to be.
He wasn't allowed in the house, but Mrs. Figg left him water and food on the back porch and didn't complain when he slept on her porch swing.
He loved it there even more when the Dursley's started to leave Harry there for Mrs. Figg to babysit. He would sit on the porch and watch dutifully through the glass door as the old woman showed Harry albums of her cats before falling asleep in her chair.
Once she had, he would paw at the door to get Harry's attention, and the boy would come outside to sit with him. He would talk about his day, the Dursley's, whom Sirius was growing to hate more and more each day. Sometimes he would throw a stick or ball, and damn if Sirius wasn't going to chase it to make his godson smile.
He had glasses finally, and his green eyes were just like his mother's, but he looked so much like James already that Sirius sometimes felt his heart being torn out of his chest.
When Harry was eight, somehow Sirius managed to get into the Dursley's house. His godson lead him through the front door and Petunia screamed, and Harry asked if he could keep him.
"No! No! Get that thing out this instant! You stupid boy! That's not even a dog, it's a bear! A bear!"
There was a lot of yelling, Sirius kept his head low, torn between pretending he was a good boy and snarling or snapping at anyone who came close to his godson. He went for the first route and laid himself down, his body trembling from the force it took not to lunge at Vernon Dursley's fat neck.
"If I can keep him I won't talk for a whole two months," Harry said, "and Dudley can have all my desert until I'm ten."
Vernon appeared amused at the proposal, deviously so, "One word out of you and the mutt goes!"
Sirius felt proud of Harry for managing that, but sick at the same time. He expected to be brought to a bedroom, and instead Harry opened a door under the stairs and scooted in before patting the area beside him on the bed that had been shoved in there.
The moment Sirius had jumped up, Vernon had shut the door, and Sirius was utterly horrified when he heard the lock engage and the grate shut with a yell of "not a word!"
Sirius moved between lying on the bed and lying on the but of ground between the bed and the door. Harry kept to his word and remained utterly mute for an entire two months when he was with his family.
The only time he spoke was deep into the knight, with Sirius curled up on the bed and sharing the pillow with Harry as he whispered stories and told Sirius about his day, about muggle school, about the kids bullying him.
"I need to name you, you know?" Harry whispered the first night, "If you're gonna be my dog from now on. What do you think? Spot? Shadow? Spike?"
Sirius snorted loudly and shook his head, ears flapping. What kind or names were those? Harry had definitely inherited his father's pension for bad titles.
"Alright, what about Bolt? Or Ace?"
Harry fell asleep halfway through his long list of absolutely horrible names, and Sirius, for the first time in years, transformed back into himself.
There was no way he was going to live there if Harry was going to give him a dumb ass name like Apollo, Bo, or Benji. So he found a notebook and scribbled down all the names Harry had thought up before writing down "Padfoot" at the bottom and circling it a few times, then transformed back and curled up at Harry's feet.
The next morning Harry was very confused ("Did I write this down? I must have.") But he didn't question it and just settled for the name he must have circled.
"I don't know why I liked Padfoot so much last night, it's a weird name isn't it."
Sirius was greatly offended by it, but there was something warm and nostalgic at the way Harry called him "Pads". It made him even happier when Harry told Vernon his name, because it made his face red in fury.
"What a stupid name! Unnatural! Ridiculous!"
For the next few years, Sirius acted as Padfoot, the Stray taken in by the Dursley's but owned by Harry. He was happy to be with his godson, that was all he wanted, but little things made him so made that sometimes he couldn't stand it, and more than once he nearly transformed to hex the faces off of the Dursley's.
Sirius was kicked out of the house whenever Harry was at school, which was well and good in his opinion, for it allowed him to remain close at all times, watching his godson in the playground and sneaking out to join him when no one was looking. He nipped at the kids who bullied Harry, never actually biting them because then he could get in trouble and wouldn't be able to stay with Harry.
When Hagrid first came on Harry's eleventh birthday, Sirius worried maybe he'd be found out, but instead Hagrid only marveled at him (massive dog, got one of my own, name of Fang, you'll meet him soon Harry!).
Sirius was stuck out of the house for the next year, waiting patiently for Harry to return with news of Hogwarts, happy that they had moved to a bigger room up the stairs, likely to appease Dumbledore. Sirius liked it much better than the little cupboard, and he liked the gorgeous snowy owl that Harry had dubbed Hedwig.
He sat and marveled as his godson showed off pictures of his new friends and told him stories about magic, revealing his wand and wisely saying he wasn't allowed to use magic outside school but don't tell the Dursley's.
His favorite thing was the scrapbook Hagrid had given him, filled with pictures of James and Lily, one framed and sitting on his bedside table that Sirius would sometimes sit and stare at for hours on end, blankly, pitifully.
The second year, when the house elf appeared, and Ron Weasley came flying in a car to rescue Harry, he was urged into the car just as Vernon came crashing through the door, sitting on Harry's lap as they flew in the Ford Anglia towards the Weasley home.
"That's one gnarly mut, Harry," one of the twins noted, and Harry wrapped his arms around Sirius.
"Massive. And scary," Ron wavered, "Mind keeping him away from Scabbers, do you? Don't mean to be mean, but-."
"Alright Ron, Pads is used to being outside. That okay?"
Sirius nuzzled his bangs, nose against Harry's scar, because no he didn't mind, because they were out of that house and Harry seemed very excited.
Truly the Burrow was a sight to behold, Sirius thought it brilliant, and Molly Weasley didn't mind him as much when she found him chasing gnomes out of her garden. She though it was excellent, offering him bits of bacon as a reward, and Sirius was all too happy to stay there when Molly offered.
"We'll look after him while you're away, Harry darling, make sure he's well fed and exercised. Scrawny and scruffy thing."
Sirius wasn't that excited when Harry, Ron, and the twins were tasked with bathing him, because he wasn't allowed into the house until he was scrubbed clean, complaining the entire time he was being hosed with jets of water and soap and head stooping in complaint when Harry and Ron set about combing the tangles from his black fur.
Only made worse when Ginny started tying bows into the fur at the top of his head while Fred and George laughed themselves sick.
Sirius was a good pet, he was patient and he was enjoying being with Harry, helping him as well as he could, but there were things that he just would not stand for. A year later, the newspaper that Harry recieved from Ron in the mail, that showed the Weasley family in Egypt, had Sirius sick in anger. There on Ron's shoulder was a rat, and Sirius recognized him, as many times he'd seen him transform.
He left that summer, and made the mistake of transforming and being seen by the public, and the next thing he knew his face was being plastered in the Daily Prophet and even the muggle news. Murderer Sirius Black, twelve years a fugitive, spotted after so many years.
He couldn't get close to Harry after that, people were watching out for him now, so he could only follow from a distance, traversing the cruel countryside on his way to Hogwarts and hiding out in the Forbidden Forest, waiting for his chance.
He saw Remus there, for the first time in so long, so many years, and something in his heart both shattered and swelled. He looked aged, tired, but he looked at home, like he belonged there at Hogwarts, as the DADA professor. Like it was truly what he was always meant to do.
During the full moons Sirius sat at the edge of the forest waiting, watching, just in case, in case Remus needed him, but he never saw him wandering thr grounds. Sirius only hoped he was okay.
Many times he'd see Remus walking alone, limping, a walking stick in his hand that he leaned heavily against. Sirius trailed after him and stayed in the shadows, watched after his old friend.
His favorite moments were when Remus walked with Harry, talking, many times talking about James and Lily, and Sirius was so happy that Harry had someone he could talk to about his parents, who knew his parents as well as Remus did.
Harry didn't seem all that worried over the Grimm prophecy that he discussed with Remus, shrugging casually.
Harry: That's not a Grimm, that's my dog, Padfoot.
Harry: Yea, but he ran away just after school got out last year. I hope he's okay.
We all know how oblivious Harry is though.
"The Mauraders map has my dogs name on it, how weird."
The rest of the year goes by the same as in the books, Sirius ends it by escaping with Buckbeak and Harry is left very confused but very happy.
"I guess my godfather was with me all this time after all, looking out for me."
"It's only a little weird that he was a dog for like, twelve whole years."
"And slept on the foot of my bed."
Remus: He did that when we were younger too. Sometimes he did it when he wasn't transformed. I don't think he realized.
Sirius: Remus he wanted to call me Spot.
Sirius: It's not funny, Moons.
