AN: Written for the Wand Wood Challenge Prompt: Red Oak - Write about an animagus.
Sirius Black was innocent, he knew it, he just had to hold on to that thought and remember it. They say that many people go insane in Azkaban, but Sirius refused to be one of them, anything that he could use to keep a hold of his sanity against the dementors was something that he would try. Holding on to the fact that he was innocent determinedly was one of them, if he tried not to think on his memories or emotions then maybe he could keep them from the dementors that guarded his cell. A single thought of a statement of fact was something that they couldn't rob from his mind, not if he believed it soul deep.
And believe it he did. He was innocent of everything that he had been sent to prison for. Betraying the Potters to Voldemort, he would never do that, James was his brother in all but blood, one of his brothers by choice. Killing Peter Pettigrew and twelve muggles, well unlike the rest of his blood family he had nothing against muggles or muggleborns, he certainly wouldn't go about murdering them en-masse. Peter Pettigrew on the other hand, well he wouldn't mind killing him, now that he had shown his true colours and betrayed his friends to Voldemort, Sirius was sure that he would even enjoy it. It would be one of the first things that he did when he got out of Azkaban, if he got out of Azkaban.
The fact that he hadn't had a trial also helped him in a way, although if he had a trial he wouldn't be there in the first place, but he had never been convicted as being guilty, just tossed into a cell on the dark island. He used anything that he could to his advantage and the biggest one that he had was his animagus form, Padfoot the grim. Grim's were creatures of the shadow, and were slightly less affected by the dementors than a human wizard. It helped him keep his sanity by hiding in his dog form whenever he could. It meant that he ran the risk of merging more thoroughly with his animagus form and taking more of his animal traits on in his human form, but that wasn't such a hardship when compared with the alternative. Many people had been saying for years that he was a dog anyway.
He couldn't stay in his animagus form all the time though, he certainly would if he could, Azkaban was much more bearable as a dog, but the human guards couldn't be allowed to see his other form. The dementors have no eyes, so it wasn't like they were going to report him, but the guards could see to it that his magic was bound or restrained which would stop him from being able to transform. No, he would have to be careful with his transformations so that he wasn't discovered and then unable to change and find any respite from the cold cell on the dark island.
He hoped that he wouldn't be there for long, that Remus would question his supposed betrayal and insist on a trial for him. The other man was all about justice after all, even if he thought him guilty, which he probably did given the circumstances, he would want to see that justice was observed properly, for him and for Harry.
Sirius couldn't believe that he had left Harry to rush off after Peter, he had put thoughts of revenge above the needs of his godson. It was one thing to be angry and furious about the rat's betrayal, but at the same time he had betrayed the oath of care that he had taken towards Harry. For that alone he deserved some punishment, but Azkaban was a bit too extreme.
As he transformed into Padfoot he wondered about where his pup was now that he was in prison and James and Lily were both dead. He had probably been taken to Alice, she was his godmother after all, but Moony was another choice. Lily had also listed Snape as a guardian, Sirius really hoped he was with Alice or Remus, then his godson had less of a chance of hating him.
He curled up in the corner of his cell, hoping that the fur of his animagus form would keep him warm throughout the night, but doubting it at the same time. The dementors began to sweep down the hall now that the human guards had retreated for the evening. They would stop as they reached occupied cell before moving on again and then repeating the action over and over again. Sirius watched from his position in the corner, glad that he was able to recognise what they were doing and not feeling as much of an effect as the other inmates who were screaming in their cells.
Waking up the next morning Sirius made an important decision, not only to let the dementors get him down, but to make sure that he made the most of his time in Azkaban. There wasn't really much to do his small cell, but he wasn't going to let himself go completely idle, he was likely to lose himself to insanity through that just as much as the dementors. When awaking he would run round his cell for a while in his animagus form to try and keep up with some sort of exercise program, before he would transform back into his human state before the guards started making their rounds. Between the meagre meals he would plot and revise. Between breakfast and lunch he would mentally review everything that he had learned about magic, there was no need to lose the knowledge just because he no longer possessed a wand. The time between lunch and dinner was spent plotting what he would do when he was released, but before long that became when he escaped. It took him years before he managed it, but when he did his first thought was to check on his godson to make sure that he was okay before tracking down the betrayer and making sure that justice was served.