You know the story, about the murderer, Sirius Black. Secret Keeper of the Potter family, the one sworn to protect them at the cost of his own life.
Sirius was innocent. He switched with Peter Pettigrew, thinking that the Dark wizard Voldemort would go after him.
Peter betrayed the Potters, leading to his friends' deaths and the orphaning of their son, Harry. However, Sirius was blamed for the crime, as no one had known of the switch. He was sent to Azkaban, where he spent 13 years biding his time before escaping and setting the record straight as far as Harry--and Remus--were concerned.
Remus Lupin was the love of his life, even when he knew the other man thought him a murderer. Sirius was never a bully. A braggart and a git, yes. But he never saw the purpose of needless cruelty. He received too much of that at home.
He was murdered by Bellatrix Lestrange. He was cast through the Veil in the Department of Mysteries.
Sirius arrives at otherways just after that moment.
[ooc: Sirius Black is the property of J.K. Rowling and is from the Harry Potter universe. He does not belong to me and no copyright infringement is intended. Mun journal: dawning_star.]