Hester is the main antagonist of the first volume of the Buffy The High School Years graphic novels, Freaks and Geeks.
Not much is known about who she was as a human but, she and her friends, Lisel, Stephen and Greg, have not been vampires long with the story implying she likely fell victim to one of the numerous vampires in the city then fed on her friends not long after with the group having holed up in a cemetery turning. Despite losing their humanity, they mostly stayed the same as a pack of geeks, playing board and video games at night when not hunting. However it's likely the corruption made Hester more aware of her status as this.
One night her friends and she tried to get into a club exclusive for vampires but were denied entry for their lowly status. Demanding to be let in, she asked if there was anyway the bouncers would do so with one of them jokingly suggesting to kill the slayer (largely out of annoyance for her attitude and hoping Hester and her friends would get staked). She took it to heart and convinced her friends to join her. They happened upon Buffy while she was hunting, overhearing Xander and Willow discussion about Buffy's former school days as a pampered queen bee. Once the two had left, the group attacked Buffy and were no match, However Hester managed to catch her off guard by lying about Willow claiming not to like her, this made Buffy hesitate and the group knock her down before escaping. Embolden by this, the group resolved to finish the job with Hester revealing she got a spell book online to help them.
In the final confrontation, where they dressed in very goth like clothing much to Buffy's amusement, the slayer once more dealt with then handily calling Hester a hypocrite due to just ordering her friends around, Hester had her friends surround her and enacted a spell to summon a demon. However she didn't tell her friends that they were to be used as sacrifices in order to do so, much to Buffy's disgust that she callously made them pawns just to selfishly boost her own status and acting purely out of peer pressure. Hester cited them as "losers" and tried to command the demon to attack Buffy. However the demon revealed that Hester didn't read the spell entirely as she needed four sacrifices to control it, having only given up three and chastised her for using magic she wasn't familiar with, Hester could any stand stunned at her mistake before the demon crushed her, leaving Buffy to deal with and ultimately kill the demon with the help of her friends.