Captain Swan AU. Cora lets the curse take Killian, and her action changes the course of events in Storybrooke, forever changing their lives. A lot will stay to canon to Seasons 1-3 so far with exceptions made to accommodate Killian being cursed to Storybrooke as well as original scenes with Killian and others. There will be elements of season 4, but I will not have canon season 4.