So I had a thought whilst re-reading Prisoner of Azkaban.

Sirius mentions that being a dog helped since the Dementors didn't affect him as much in his dog form.

So I had a thought: What if the reason Dementors don't affect him in Padfoot form is due to a more limited range of emotions and thought. How would spending thirteen years as a dog inhibit or affect Sirius? What kind of personality would he acquire? A more basic and primal presonality, what kind of problems and hardships does he face?

Or does it help him mentally? Is he able to let go of issues and problems more easily?

Basically: How does the experience of being a dog and feeling its emotions and thoughts for 13 years affect Sirius mentally?

One-Shot or Novel, doesn't matter though it's probably better as a one-shot. PoV doesn't matter either as long as we see that Sirius has been greatly affected in some way. I know that staying in a prison that long will do some damage no matter what, I understand that, but I'm more curious of the repercussions of remaining in Animagus form for extended periods of time.

 

"Ron – are you okay?"

"Where's the dog?"

"Not a dog," Ron moaned. His teeth were gritted with pain. "Harry, it's a trap –"

"What –"

"He's the dog… he's an Animagus."

Ron was staring over Harry's shoulder. Harry wheeled around. With a snap, the man in the shadows closed the door behind them.

A mass of filthy, matted hair hung to his elbows. If eyes hadn't been shining out of the deep, dark sockets, he might have been a corpse. The waxy skin was stretched so tightly over the bones of his face, it looked like a skull. His yellow teeth were bared in a grin. It was Sirius Black.

He barked.