Sunnydale HighHarmony Kendall was a student at Sunnydale High, and before that, it is stated that she has been in Sunnydale for a good ten years, as Willow says in "Graduation Day, Part One" that even though they signed each others year books and exchanged pleasent conversation, Willow mentions after she leaves that she bullied her for ten years and that she hated Harmony.
Harmony was a member of the famous "Cordettes", and was the best friend of Cordelia Chase, until Cordelia begins dating Xander Harris, and Harmony forces her out of the gang and she goes and joins the Scooby Gang. Harmony, from then on, is the main Cordette, and leads the gang of popular girls. Although, after Cordy and Oz walk in on Xander and Willow kissing and Cordy is impaled on a bar, and she then tries to rejoin the Cordettes, Harmony humours her, before finally revealing that it was all just a spiteful joke. As Harmony humours her, when she mentions that Cordelia should start dating again, she reveals that she was mocking Cordelia, and mocks her and Jonathan Levinson. She is then seen laughing cruelly at Cordelia after she had been knocked into a pile of rubbish and later several times in school. However, when the reality switch happens, Harmony no longer leads the Cordettes and continues to live her life under Cordelia.
Harmony's next real appearance is in the season three finale. After signing Willow's year book (see above), she is then later found in the second part of the episode, when Xander finds her, takes her away and we can assume fills her in about graduation and the plan. She is then seen fighting in the Graduation Day battle, but we see her being viciously sired on screen by a vampire, but her fate isn't revealed until the next season.
Next season, in "The Harsh Light of Day", where she appeared to Willow. The two talked for a minute, and then Harmony revealed herself to be a vampire, and tried to sire Willow. Luckily, Oz arrived and warded Harmony off and she only managed to bite Willow on the neck. Harmony then rants about hwo her new boyfriend will kill them for this, and she runs off. Later, we discover that her new boyfriend is Spike, who's looking for the Gem of Amarra below Sunnydale. Harmony is seen to obviously annoy Spike, but for some reason, their relationship seems to thrive on this and Spike's anger. After breaking through into chamber of jewels, Spike frantically looks for the Gem, while Harmony basks in the amazement of the jewels, trying as many as them on as she can. She suddenly annoys Spike so much, that he stakes her. But, she regenerates, wearing the Gem in a ring. Spike steals the ring and storms off. Harmony is later seem walking around the College Campus with Anya and Buffy, all three heart broken.
She's later seen again, after Spike escapes the Initiative and returns to his Crypt. Harmony is over the moon to see her "blondie bear" back, but, he instantly leaves to go chasing the Slayer. Xander
the next time Harmony is seen, she is a vampire. Harmony runs her own vampire gang for a while, and, when that goes south, she started dating Spike, who was on a campaign to kill Buffy. The relationship was a rocky one at best, with Spike being an abusive boyfriend who was secretly in love with Buffy. Harmony eventually had enough of Spike and left him.
Wolfram & Hart Harmony drops off the grid for a while before showing up in LA at Cordellia's doorstep. Cordy lets Harmony stay with her, unaware that Harmony was a vampire. However, Harmony's intentions are relatively pure, and so she was not slayed when everyone found out.
Harmony is next seen working at Wolfram and Hart under Angel as his new secretary.
During that run, Harmony was involved in several hilarious antic dotes, including a situation in which she got drunk the night before and couldn't remember if she had fed (bit and drank from a human, which was against Angel's rules) on a corps that was found the next morning by Angel and his people.
Harmony worked for Angel loyaly until the day he went up against the senior partners, at which point she had him sign her relese papers.
Buffy the vampire Slayer: Season Eightin the season eight comic, it is discoveed that Harmony has become a celebrity. Apparently, she bit a talent agent, and he liked it so much he pitched the idea for a MTV vampire reality tv show called "Harmony Bites". the show did ok at first, but people eventually grew bored of it.
Durring a party for the show, a newly-cristened slayer who didn't work with Buffy attempted to slay Harmony. Harmony beat and killed the slayer on Live TV. However, instead of this being a bad thing, MTV spun it, and the world began to hate Slayers, with Harmony as the main advocate.
Powers and AbilitiesHarmony has the standard powers and abilities of a Buffyverse vampire. She has superhuman strength, speed, reflexes etc. and is vulnerable to light, fire, decapitation, holy items and wood through the heart. Like others of her kind, Harmony's personality changed after she was sired, but not greatly. She was still self-centered and obnoxious and confident, but no had a severe lust for blood and torture of others.
But, unlike other vampires, Harmony admits she lacks martial arts skills. She has been seen several times attempting to fight others, but not completely to her avail. When Marcus Hamilton came to with the contract for Eve's immortality, Harmony tried to fend him off by jumping on his back, and nothing more (granted, he was very very strong). When fighting another vampire who was after her job, she and Harmony merely had a catfight, but their superhuman strength knocking each other through walls. And she and Xander slapped each other for a while, but this isn't necessarily viewed as a proper fight.