Disclaimer: I don't own Sirius. I only borrow him to write angsty stories
Sirius doesn't remember.
Sitting in a small, cold cell, Sirius doesn't remember. He doesn't remember kissing pale freckles on Sunday mornings, warm soup brought to him while lying sick in a bed with red hangings, never ending hugs from friends after summers spent in a house he doesn't belong in and father- and mother figures in the most unlikely.
He really doesn't remember a flat to small and cold which later become cozy and loving, a best friend who was more like a brother than his biological one, a annoying redheaded perfect who later gave birth to their future and a love so wonderful his heart broke just thinking about losing it.
Sirius doesn't remember because remembering brings the Dementors. Black things floating outside the bars to the cell, giving the memories just enough time to warm him before stealing them away, mocking him with them, daring him to remember more.
But after twelve years of not remembering, there is a paper and a betrayer and the memories come rushing about a rat that fouled the all. And this time the dementors doesn't come and steal them because this time the memories doesn't warm him, they are not happy, these memories is about hate, suspicion and death but most of all they are about revenge to come.