Eve is a villainess from the Buffy the Vampire Slayer spin-off, Angel.
Eve was "liaison to the Senior Partners" of Wolfram & Hart after Angel and his crew takes over the Los Angeles branch of the firm. Never trusted, she comes and goes at her leisure, usually stirring up trouble as she goes. Though she appears human, Eve is actually a Child of the Senior Partners, a being given human form and created to do their bidding.
Though Eve has sex with Angel once, under mystical circumstances, at some point she meets and falls in love with Lindsey McDonald. The two hatch a scheme to slowly but surely demoralize Angel through a variety of means. Eve and Lindsey use a spell to make Angel and his team believe that the existence of two vampires with a soul endangers the existence of the universe, then manipulate Spike into becoming a vigilante and reminder of the work Angel used to do. Eve frequently mentions Spike's new status as champion when he is re-corporealized, and even puts a parasitic creature on Angel that sends him into a world of illusions, in which Angel has become a loser and Spike the champion.
The plan all along is for Spike to save Angel from the agent, but unfortunately for Eve, Angel, in a moment of cognizance, recognizes Eve as she unleashes the parasite. Although she tries to talk her way out of it, Angel and his friends trust her even less now. The revelation that she has been working with Lindsey against Angel puts her on the run. Eve hides in Lindsey's apartment, using the runes covering it to remain beyond the Senior Partners' radar.
Eve's position with the firm is ended when she is confronted by the new liaison, Marcus Hamilton, and forced to sign away her immortality. She comes under the legal protection of Angel, as Angel believes she can be useful against the Senior Partners. Lindsey eventually returns from his own prison, thanks to Angel, and the two are able to spend some more time together before Angel approaches Lindsey for a final mission against the Circle of the Black Thorn, and Lindsey agrees to join in the battle.
Eve is skeptical of Lindsey's chances of survival during the last battle, and Angel's enigmatic words that he isn't going to return only emphasize it (Lindsey is ultimately assassinated by Lorne). Lorne himself had, at a previous meeting, prophesized that Eve has a terrible future ahead of her, and it seems to be coming true, having lost her job and her love with no where else to go, she remains in the crumbling Wolfram & Hart offices when they are destroyed, asking where she should go.