A detail of what went on when the Marauders first arrive at Hogwarts. It focuses on how Lupin reacts to Sirius' high-class social status, and how Sirius perceives his new friend's extreme poverty. NO SLASH WHATSOEVER.
After the Triwizard Tournament, Sirius is dispatched to find members for the new Order of the Phoenix. Meanwhile, Nymphadora Tonks is bored out of her mind, but is in for the surprise of a lifetime.
It's a diary of sorts. There's one entry for every Christmas of Sirius' life, and he tells about what's going on in the world from his point of view, no matter where he is or who he's with. This diary follows Sirius till the end of his life.