The Slayers

Lady Genevieve Savidge is a girl from british aristocracy. When Buffy Summers was fighting against the forces of the First she has her ally and friend Willow Rosenberg use the power of Buffy's scythe to activate the potential slayers to turn them into a slayer any girl who may have been chosen know was and "Gigi"was among those  who gained the powers of the slayer. However even though she was a potential that didn't mean she was going to make a good slayer like the slayer after Buffy Faith she was sick and twisted and could not be helped.

She has been kidnapping girls and hunting them calling it a "foxhunt" including a newly called slayer. Rupert Giles aware of this fact chose to go down a darker path and decided not try and fix her but get rid of her. Instead of going to Buffy with this or any of the other Scoobies he asked Faith to kill her. He knew Faith has the right mind set to do something like this and since she knew the evils that come with an evil person with that much power it made her almost perfect to kill her.

Faith

Giles prepared Faith to assassinate Gigi at a party she was hosting for her 19th birthday and even taught the slayer a few thing about how to act in high society. Faith makes it pass the security and even acts the part of snooty girl with too much money. However Faith is feeling different about killing Genevieve and even though she has a knife in her hand she pulled from her hair she is nervous about the assassination and soon Roden Genevieve's irish warlock watcher uses Gargoyles to watch Faith.

Unable to do the deed Faith goes outside to get a smoke but while she's their Genevieve sneaks up and joins her. Faith begins to talk to her under an assumed name (Hope Lyonne). She tries to kill Gigi again but this time the Gargoyles show up and stop her. But Faith was able to kill the beast but she passes out after the fight. Roden and Gig take her back to Gigi's home. Roden thinks that she is to dangerous.

Kill the Queen

 But Genevieve actually became fond of Faith and wanted her to join her in her bid to become "Queen of the Slayers" and kill Buffy not the queen of england like she originally thought. Faith (still under her assumed name) and Gigi become great friend thinking of killing Buffy. The two even take a bath together. During Faith notices that Giles really wasn't sending her on a mission to save the world but just to save Buffy but she wanted to still kill Genevieve.

However Giles soon began to believe he had lost control of Faith and she was really working with Genevieve. Soon Genevieve and Roden used a spell to bring Buffy to them from her base in Scotland. She starts to fight Buffy but loses due to Buffy's better years of training and combat. Faith's true identity was eventually exposed after Genevieve made her failed attempt on Buffy's life and Buffy did almost die by Faith's hands during the fight but she was able to calm down and Willow teleported Buffy back who immediately wanted to speak with Giles. 

Genevieve was devastated by Faith's betrayal and the two slayers fought. The fight carriers on to the greenhouse while Faith tries to get Genevieve to leave Roden and work with her but she will not listen and is being stubborn. Gig even jams her axe in a tree and tries to take on Faith herself but after a vicious battle and a kick to the stomach Faith accidently impaled Genevieve on her axe. Roden refused to heal her wanting to replace her with Faith and causing her to die.

Powers

As a slayer she has all the usual powers of a slayer. She has increased strength and speed enough to kill most types of demons and vampires. She would experience the normal visions that a slayer would have telling her of her past as a member of the slayer line. She was no doubt trained in combat and weapon use by her warlock watch Roden and was seen able to fight Buffy for some time despite her experience and years of practice.