butterfly effect, n. 1. A tenet of chaos theory that describes how small actions can have large effects. 2. A Final Fantasy VII AU working off this premise. When a little blond boy awakens an old Turk from his long sleep, no one could've guessed how things would change.

After the events of Halloween 1981, Sirius Black finds himself raising Harry, with the assistance of Remus, in a world where Voldemort never disappears for 11 years.