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".
Angel (Buffy the Vampire Slayer)
In "Angel"'s fourth season (2002–2003), Angel is rescued from the ocean by his former friend Wesley. As Los Angeles crumbles under signs of the apocalypse, Angel is forced to cope with the romantic relationship between his son and Cordelia. In order to find out more about the Beast (Vladimir Kulich) terrorizing L.A., Angel Investigations remove Angel's soul and bring back Angelus after a vision from Cordelia suggests that Angelus has history with the Beast that Angel does not remember. Angelus, however, manages to escape, kills the Beast for fun and wreaks havoc until an old friend, Willow, manages to return his soul for the second time. It is eventually revealed that Cordelia has been possessed by the Beast's master, Jasmine (Gina Torres), a higher power who manipulated many events in Angel's life in order to be born in this world. Once born, she puts humanity under her thrall in the hopes of achieving world peace. When Angel restores free will and ruins Jasmine's plan, Wolfram & Hart offer him control of their L.A. branch as a reward for putting a stop to world peace. Angel accepts when they agree to rewrite Connor's memories of growing up in hell, allowing him to live a normal life with a new family. Afterwards, Angel appears in the penultimate and final episodes of "Buffy", presenting Buffy with an amulet to help her battle the First Evil which is given to Spike.