Faith Lehane

Born to alcoholic parents, dropped out of high school
1998: Called as a Slayer, gained her powers;
Watcher was murdered by Kakistos, retreated to Sunnydale;
Allied with Buffy Summers & the Scooby Gang, killed Kakistos together
Accidentally killed a human while on patrol, went rogue
Joined Mayor Richard Wilkins, helped him to carry out his Ascension
Critically injured during a battle with Buffy & put in a coma, awakened 8 months later
Hired to kill Angel in Los Angeles by Wolfram & Hart, tortured Wesley;
Tried to get Angel to kill her instead, remorseful of her past deeds
Came to terms with her past & willingly surrendered herself to the police
2003: Broke out of prison to assist with containing the recently released Angelus
Returned to Sunnydale to assist in the battle against the First Evil
Stationed in Cleveland after all potentials were activated
Joined forces with Giles to prevent more Slayers from going rogue