♥ thank you! I was really hoping I crafted a wonderful story through the telling and I'm glad you did.
Why the Lily changed their minds is that he was originally on trial for the murder of Dumbledore. Not necessarily war crimes, but that specific incident. Showing the memories of Lily and how utterly loyal he was is what did it. The Lily memories are what show his utter loyalty to Albus, particularly when he swears he'll do anything to erase past transgressions. Does that make sense?
In any case, ♥ Thanks for reading and I'm glad you enjoyed it!