"No," he said. "I know that you think you know everything but you know nothing at all." He rubbed his eyes. "I'm not denying that it was James Potter in the Shrieking Shack with me that night. I'll also tell you that that map, the Marauder's Map, was created by my friends and me while we were at Hogwarts. James Potter was one of them. I know he didn't give you the map because, like I said, we lost it seventh year. I also know that Fred and George Weasley managed to get it back sometime in their tenure here. I never took it from them, even though I knew what it was. And I see absolutely no reason why they would have given it to you rather than their sister."
Sirius sat back and looked at her, tiredly, exhausted really, open and vulnerable. "James Potter is my best friend, and I'd die for him. Much in the same way, I'm assuming, you'd die for your mother, or for Mr. Longbottom, am I right?"