Buffy the Vampire Slayer
Not all vampires were evil in the series.  One vampire was named Angel. He was given his soul back by a gypsy curse.  The curse would make him lose his soul and become evil again if he became really happy.  He and Buffy fell in love. The curse took his soul away when they had sexual intercourse for the first time. This caused Angel to become evil (losing his soul).  When Angel got back his soul, he knew that he and Buffy could not be together because he might lose it again.  Angel left Sunnydale and went to Los Angeles. The television series Angel tells the story of what happened to him after he left.