Harry sighed and ran a hand through his hair. Lovely way to have this conversation, he thought. Me in nothing but my shorts, about to tell my godfather that he was falsely accused of a crime he didn't commit, and the person he trusted in keeping my family safe was the traitor.
"It's kind of complicated." He admitted, "I'm not sure where you are in your history, but I assume that... that my mum and dad are still alive in your time. You told me, when I was thirteen, that you thought Remus was a traitor, that he was working for Voldemort. Well, someone in your circle was working for Voldemort, but it wasn't Remus.
"You were the decoy Secret Keeper for my parents. They had chosen you, but you thought that everyone would be after you, and that they would torture you until you told them where they were living."
This was hard, without making it sound like Sirius was at fault. Harry wasn't sure how else to tell the story, though, other than what Sirius and Remus had told him.
"So, you somehow convinced my parents to use you as a decoy and Peter Pettigrew was the real Secret Keeper. Unfortunately, it turned out that Pettigrew was working for Voldemort. He let Voldemort into the house, he killed my father, and came upstairs for my mother and me. He gave Mum the option of living if she let him have me, but she refused. He killed her, and then tried to kill me."
Harry lifted up his fringe to let Sirius see the now faded lightning bolt scar.
"Dumbledore told me when I was older, that the only reason I didn't die when he cursed me was because of my mother's love. I believe there were other forces at work that stopped him from killing me, but that's a story for another time.
"Anyway, when you found out about Pettigrew getting my parents killed, you went out in search for him to get justice. You found him in Muggle London, in a crowded street. He cut off his finger, and killed thirteen muggles in the street before escaping as Wormtail. You were arrested for murder, and were sentenced without a trial to Azkaban for life."
Harry took a deep breath. That part of the story was over. Now, for the questions.