Angel (season 1)
At the end of the third season of "Buffy", the 242-year-old, re-ensouled vampire Angel left Sunnydale to give teenage Slayer Buffy Summers the chance to live a normal life. Angel is now living in the big city of Los Angeles. With Buffy gone Angel is now completely cut off from society, every day getting closer and closer to giving in to his vampiric hunger. It's not until he befriends the half demon and fellow Irishman Doyle, who is sent visions of people in trouble by The Powers That Be, and fellow Sunnydale resident Cordelia Chase, who grounds Angel's life in the humanity around him, that he truly begins to take charge of his life and seek atonement for his past sins. He sets up his own detective agency, Angel Investigations and begins to "help the helpless".
Buffy the Vampire Slayer
The emotional stakes are raised in season two. Vampires Spike and Drusilla (weakened from a mob in Prague, which, it is implied, caused her debilitating injury), come to town along with a new slayer, Kendra Young, who was activated as a result of Buffy's brief death in the season one finale. Xander becomes involved with Cordelia, while Willow becomes involved with witchcraft and Daniel "Oz" Osbourne, who is a werewolf. The romantic relationship between Buffy and the vampire Angel develops over the course of the season, but after they have sex, Angel's soul, given to him by a Gypsy curse in the past, is lost, and he once more becomes Angelus, a sadistic killer. Kendra is killed by a restored Drusilla. Angelus torments much of the "Scooby Gang" throughout the rest of the season and murders multiple innocents and Giles' new girlfriend Jenny Calendar, a gypsy who was sent to maintain Angel's curse. To avert an apocalypse, Buffy is forced to banish Angelus to a demon dimension just moments after Willow has restored his soul. The ordeal leaves Buffy emotionally shattered, and she leaves Sunnydale.