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 season two (2000–2001), Angel discovers that Wolfram & Hart has brought his sire and former lover Darla (Julie Benz) back from the dead in human form. Although Darla is intent on bringing back Angelus, Angel hopes to save her soul and help her seek redemption while she still has a chance. However, just as it looks like he might succeed, Wolfram & Hart bring in Drusilla to turn Darla back into a vampire. Angry at the lawfirm and embracing his darker side, Angel fires his employees, Cordelia, Wesley (Alexis Denisof) and Gunn (J. August Richards) (secretly to protect them from this dark territory, as he later revealed to Lorne (Andy Hallett)), and embarks on a vendetta against Wolfram & Hart, even allowing Darla and Dru to massacre a group of lawyers. Eventually losing faith in his mission, Angel has sex with Darla in the hopes of losing his soul. Instead, he experiences an epiphany and realizes that the good fight is still worth fighting. A disgusted Darla flees L.A. and Angel reconciles with his friends, who eventually forgive him. Angel also appears in "Buffy" season five's "Forever", comforting Buffy after her mother's death.