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".
Faith (Buffy the Vampire Slayer)
Faith returns to "Buffy" for two episodes in the fourth season. Waking up from her coma, she seeks revenge on Buffy by switching their bodies using a mystical device called the Draconian Katra left to her by the now-deceased Mayor. As Buffy is taken into custody by the Watchers' Council for crimes she did not commit, Faith discovers for the first time what it is like to be surrounded by loving friends and family, and Buffy starts to understand Faith despite being upset with her predicament. After feeling obliged to rescue a church full of people from vampires, Faith battles Buffy once again, expressing extreme self-hatred before being returned to her own body. The storyline is continued in the first season of spin-off series "Angel", as Faith escapes to Los Angeles and is hired by Wolfram & Hart to assassinate Angel. Instead, she plots an intricate plan to have Angel kill her, but Angel convinces her to face the consequences of her actions, bonded with her as a friend and ally due to their similarities, and helps her on the path to redemption. Faith hands herself over to the police and she is sentenced to a women's prison, where Angel later visits her.