Synopsis
Buffy Summers was The Slayer. By day, she was a normal girl, going to school and going shopping with her friends, but by night she was the Chosen One - One girl in all the world chosen to fight vampires and the forces of darkness. Buffy did the slayer thing for seven years, managing to fight all the vamps and demons that came to Sunnydale, California, home of the Hellmouth, and to look good while doing it. By the time Buffy had been fighting for seven years, she was sick of the whole "the slayer is alone" stuff, so to fight the First Evil, Buffy turned to her wicca friend Willow, who activated all the slayers in the entire world at the same time using an ancient scythe. The slayers triumphed, but Sunnydale fell into the hellmouth - literally.

Now how does Dawn fit into all this? Well, for starters Dawn Summers was, for millenia untold, The Key - a living globe of green energy with enough power to destroy the universe. But when hellgoddess Glory came looking for it, she couldn't find it. The monks who swore to protect the key hid it in the best place possible: they turned it into a human girl - the sister of the slayer, no less. Dawn had no idea of this, to her and to everyone else, Dawn was and had always been Buffy's little sister. Glory eventually came looking for Dawn, and to save her, Buffy defeated the goddess and sacrificed her own life.

Fast forward a few months, and all of Buffy's friends, spearheaded by Willow, brought Buffy back from the dead. They thought they were pulling her out of a horrible hell dimension. In reality, the pulled her out of heaven. That year, the gang tried to hold together, but Willow's addiction to magic nearly destroyed the world. If not for Xander Harris, Willow's childhood friend, she would have.

When the Slayers were activated and Sunnydale was eventually destroyed and the hellmouth collapsed, Buffy and Dawn went to Europe to try to lead a normal life. She and her sister did their best to be demonless, but when you live with a slayer, anything can happen.

It turned out that Rome wasn't as much of a paradise as Dawn had thought it would be, but Dawn finished high school there relatively uneventfully (compared to Sunnydale at least) and decided to return to the states for college in a town where there hasn't been vampire activity for 100 years. But it's never easy for Summers' women. . .