A pained laugh escaped his throat. Only because that response was so incredibly Sirius; the Sirius who Remus had known since childhood and loved with every beat of his heart and breath in his lungs. Merlin, it hurt. It hurt so damn bad knowing what he knew and now having to spread that pain, that poison to Sirius. He had to. If they went back to where they were from and Sirius could change things, then there was hope for at least his future, and if Remus could spare him of what was to come by informing him of what happened in his time, then it was worth stammering through the awful truth right now.
"It gets stupider, I assure you," he said; an attempt at wit, which he'd not felt surface in him in far too long.
Remus raked a hand through his hair and resolved himself to continuing. "There was a reason for the accusations, and I don't blame anyone for them. When word got to Dumbledore that Voldemort was trying to recruit a pack of werewolves to help on his side, you can likely deduce where his line of thinking led him. Especially when he realized the alpha in that pack was Fenrir Greyback." Who they all knew was who bit Remus as a boy. "The first three times he approached me about going undercover with them I told him no, that I'd never even pretend to join them. But you know Dumbledore. And you know me and how I've always felt I owe him my life for the opportunities he gave me to get an education like any other kid at Hogwarts. So I did it, but I wasn't allowed to tell anyone. Not even you. I insisted that part, because I knew if I told the others, especially you, you'd either stop me, or worse you'd follow me and get yourself killed.
"But secrets are poisonous, and that one... That one wrecked us, Sirius. I got in too deep. Even when I wanted to stop, I couldn't. I'd come back torn up from running with them on the full moons and you'd have so many questions I couldn't answer, we fought all the time. And it was killing me -- it killed me to keep it from you but I was so afraid of what could happen if you knew the truth." His eyes watered, thinking back to their fights, how desperate they both were because all they wanted was to just stop and hold each other instead of flinging their feelings at each other like curses from the tips of their wands as weapons.
"There's a missing puzzle piece to end of the war that I don't have, and I wish I did, because I can't for the life of me figure out what happened next," he said. "Before all of this happened, James and Lily got married and they had a son; Harry." To that he did smile a little. "They named you as his godfather. But when things got really, really bad James and Lily had to take Harry and go into hiding. This is where I don't really know what happened next because I was left in the dark once I wasn't deemed trustworthy. All I know is that last Halloween, their Secret Keeper betrayed them and sold them out to Voldemort. They're gone, Sirius. James and Lily are gone." Tears slid down his cheeks. "He killed them both."