Lily reached up and squeezed the hand that he'd draped around her shoulders. "I don't pretend to understand it." She said, moving herself closer to Sirius. "Why we were put through so much horror. But we knew, all of us, when we joined the Order that some of us, probably most of us wouldn't make it through." She blinked to hold back the tears that threatened as she thought of that original team- her boys, the Prewetts, the Longbottoms, Marlene McKinnon- all gone now.
"We made our choices, cast our lots for better or worse." Each of them had made an important choice, even little mousy Peter. "And we paid the price." Memories flooded back- that surge of determination as she pushed past the pain to stand between Voldemort and her tiny precious Harry. She raised her free hand to wipe away a tear.
"But-" She continued after a moment, waiting for her voice to steady. "In this second chance we have, we get to see our reward. This is a world shaped by our decisions, Sirius." A world where her final foolish act had somehow saved Harry, and he'd grown up to be just the sort of hero the world needed.
"It's our reward and our curse." She said. "You and I, we remember our most important moments, those worst moments, so through the despair we can see our triumph."