Faith: What isn't? You know I come to Sunnydale. I'm a slayer. I do my job, kicking ass better than anyone. What do I hear everywhere I go? Buffy. So I slay. I behave. I do the good little girl routine. And who does everyone thank? Buffy.
Buffy:That's not my fault.
Faith:Everyone always asks why can't you be more like Buffy? But did anyone ever ask if you could be more like me?

Faith
Apperances:
Buffy:
Season 3: "Faith, Hope, and Trick" "Beauty and Beasts" "Homecoming" "Revelations" "Amends" "The Zeppo" "Bad Girls" "Consequences" "Doppelgangland" "Enemies" "Choices" "Graduation Day pt 1 and 2"
Season 4:"This Year's Girl" and "Who Are You" when she woke up from her coma.
Season 7: "Dirty Girls" "Emtpy Places" "Touched" "End of Days" "Chosen"
Angel:
Season 1: "five by five" and "Sanctuary" when she came to L.A. fleeing from Sunnydale
Season 2: "Judgement" when Angel visted Faith at Prision to see how thing are going and to keep himself going down the right path
Season 4: "Salavage" "Release" and "Orpheus" Are the episodes that appeared when they needed help to contain Angelus and then left for Sunnydale

Faith

Faith, the vampire slayer hailing from Boston, was chosen and summoned to Sunnydale after Kendra was killed by Drusilla. Appearing out of nowhere one night at the Bronze and easily dusting a vampire. Most the gang took a liking to her right off the bat, espically Xander and her stories of wrestling an alligator naked. Faith is a wild, sexy and seemed to get off on getting the kill.
Soon after killing the Deputy mayor by accident Faith didn't care and soon after killing Mr.Trick at the time the Mayor's assistant she came to the mayor wanting to take his place. Soon after very good acting by both Angel and Buffy, in letting Faith believe that Angelus was back they find out Faith has switched sides and what they could about the mayor's asscenion.
After poisioning Angel and finding out the cure for Angel is the blood of a slayer, Buffy goes after Faith to bring her to him. She managed to use Faith's knife against her but Faith escapes as she falls from the rooftop onto a on passing truck and we find out Faith is out of commision and in a coma.
During Buffy's first year at college, while trying to track down the homicidal loonatic Adam, she gets a call, telling her that Faith has woken up and she's not in a good mood. Finding out that it's about 8 months later and learning the Mayor is toast, the school has been blown up, Angel has moved on and Buffy is with a new guy in college, it's a new world for Faith. With a message from beyond the grave, the Mayor gives a gift, in which she can swap bodies with anyone. So after a smackdown with Buffy, Faith switches bodies with Buffy. While everyone is confused includng the watchers council, eventual Buffy in Faith gets free from the council to get help from Giles, Willow and Tara who knew that Buffy wasn't Buffy. With help Buffy manages to reverse the effects and Faith runs for the hills.
Well not really...she runs to L.A. in which she is hired by Wolfram and Hart to kill Angel. When Faith tortures Wes and after another smackdown with Angel, she comes to her senses and wants to be good again. Angel tries to rehabiltate her and Buffy shows up. When trouble brews up with the council again, and Angel and Buffy argue about Faith, eventualy Faith turns herself in for the crimes she has commited.
We wouldn't see Faith untill season 4 of Angel when Wes needs Faith's help to get Angelus back into his cell in the hyperion to get Angel's soul back. Faith at first has trouble with Angelus and needs to get her edge back. Eventualy to trap Angelus she drinks poision to have Angelus drink from her and Angelus, Faith and eventualy Angel going through Angel's memories after his soul was given back to him. After Willow restores Angel's soul again, she takes Faith with her to help with the battle with the first.
And help she did, Faith did a good job helping out, even when Buffy is kicked out of the house Faith takes charge and accidently leads some of the potentials to a trap and nearly blows some of them away including herself. Coming down to the Final battle with the First and the Ubervamps beneath the school and in the hellmouth, Faith was good to have by their side and was one of the survivors to make it out of Sunnydale. Her whereabouts are unknown but it's probably a good guess that she is Rome with the others teaching Slayers.