He's not sure why it takes him three days to break. Harry mourns Sirius alone, summer before 6th year.
Everyone thought that Teddy was well over the death of his parents. However, some of his old school things- an essay on werewolves, letters to his long dead parents, show that he's not. Formerly An Essay on Werewolves by Teddy Lupin, Third Year.
When Sirius Black escapes Azkaban, he'd torn between finding Harry, seeking revenge, or trying to unite the last of the Marauders. However, the wizard is about to find that his escape is the start of a turmoil in the Wizarding World.AU, 10 year old Harry