After knowing the future tragedy, the characters from the parent generation can only return with a memory. They gave up their grand plans and chose to protect each other: James cast a blood curse to protect his wife and children, Lily believed in Snape's conscience, and Sirius remembered his trust in Remus. Under the shadow of Voldemort, they relied on these warm memories to strengthen their bond, but they still couldn't escape Peter's betrayal and that fateful Halloween.
