Twilight (Buffyverse)

Twilight is an antichrist esque entity that represents the consiousness of a dimension that is waiting to be "born".

Before the Comics
While the Twilight dimesnion hasn't existed yet, it was predicted to destroy any dimesnion that exist's along with it. It's plot say's that a Slayer that changes the world will be granted to power of a god and "give birth" to the dimension. It was a prophecy so feared that some Watchers commited suicide in fear of it's inevitable coming.

At the time the series takes place, it was one of the plans of the Wolfram and Hart law firm for the apocolypse, but they also learned to fear it.

Begining the prophecy
At the time of the comics, the prophecy was set in motion, and as it turns out Buffy Summers was a chosen slayer for the prophecy. To serves as the "Yin to her Yang", Twilight chose's Buffy's vampiric ex boyfriend Angel for this purpose.

The disembodied Twilight's entity manipultates Angel telling him the world will be destoryed if he doesn't help stop the Buffy and her allies from leading the world to chaos. Angel fell for the lies and, in a disguise, chose to represent Twilight and shared and alliance with the Anti Slayer terrorist task force. Angel, while reluctant to decive Buffy, went through with the plan with various unsuspecting minions, including some of Buffy's previous enemies.

Final Battle
Being resposnible for much of the drama in the comics, at the climax of the arc, during a battle between "Twilight's" forces and Buffy's allies in Tibets mountins, Buffy's Twilight powers are acitvated. Buffy subdues and unmask's "Twilight" and discovers Angel's secret. Angel tells Buffy his motovatin and that he loves her. Angel and Buffy give into thier passions and engage in supernatural sex, which Twilight needed in order to be "conceived".

The climax of the arc inteseify's when, Angel and Buffy find themselves in the Twilight dimension where they could shape reality, while the Earth starts to fall to natural disasters and demons begin to attack. Angel contimplates staying with Buffy, but she convinces him that thier home needs them and they return to Earth.

During the battle they are told by Spike that the source of Twilight's power is the Seed of Wonder, which is located beneath the ruins of Sunnydale. As the Scoobies head to Sunnydale, Twilight's entity confront's Angel demanding he and Buffy finish what they started and in rage, completly posseses Angel. The possesed Angel presues the Scoobies to Sunnydale, where Twilight infulances him to kill the ressurected The Master (Buffy), who was trying to protect The Seed from the Scoobies, and then Rupert Giles who was trying to destory it. Buffy beats Angel back, before destroying The Seed, a singal act that cease's the disasters, destroying Twilight's extra dimensonal demons, eraseing the dimension, exorsing Angel and killing the entity - all of which save the world from the Twilight dimension's existance.

Trivia

 * Dispite the name, the character is in no way connected to the Twilight series. Buffy's writer Joss Weadon confirmed he came up with the characters name before he heard of the Twilight Saga.