Welcome!

It's implied that Sirius never went to Azkaban. You are Y/N Minerva Lupin-Black, Sirius and Remus' daughter. For explanation, you are biologically their kid as Lily decided to be their surrogate. You're the same age as Harry (Don't ask, I wouldn't be able to explain how that's possible, but it's a work of fanfiction, anything can happen), and just to avoid any confusion, Sirius is Dad and Remus is Papa.
This book is about the misadventures of Y/N Minerva Lupin-Black and Draco Lucius Malfoy: the Duo of House Black. The book does not have a solid storyline. It will be like a one-shot book where I write fun scenarios. It also does not follow the Harry Potter series events.