107 years on this earth and Edward Cullen still isn't prepared for what it means to feels and means to be human until Isabella Swan enters his life giving him the dose of humanity he didn't even realize he needed.

It was for the Order. She'd go back in time, befriend her and lead her away from the path of evil. Sure she was a deranged, mad, Death Eater but again it was for the Order. But I don't think they factored in Hermione falling in love with Bellatrix.