Some few hundred years ago, Lilith has lost track by now (she assumes around 200 years ago), Caleb and Lilith Vatore were born. Lilith is a few years younger, but after a point, it stopped mattering. They were born in present-day Spain, near the border of France, to decent fortune and wealth. Their parents were merchants, but merchants rule the world, and more or less always have.
They grew up relatively sheltered, and almost polar opposites. Caleb has always been the more outgoing and charming one, and Lilith the more serious and refined one. It comes from the expectations of the time; Caleb had it ostensibly a little easier, being male. There were expectations that were placed on Lilith that weren't on Caleb because it was expected she marry, and marry well, and that meant being marriage material. At the time, that was quietness and refinement.
Eventually, Caleb fell in with the wrong friends, as he liked to do from time to time. Lilith knew they were dangerous, but didn't say anything right away (he liked to believe the best in people). Unfortunately, by the time they showed their colours, the woman now called Miss Hell had already turned him. Lilith went after them, intending to kill them and save her brother, and turn him human again.
That went... not so well. She apparently put up enough of a fight, Vladislaus Straud decided to turn her, because her strength would be a great asset. Unfortunately for him, she's been a spitfire and a fuck of a thorn in his side ever since, and takes great pleasure in pissing him off.
Since then, she's worked on becoming stronger, both as a vampire and generally, with the intention to eventually overthrow the mother fucker. She and Caleb lived in Forgotten Hollow with him for some time, but recently Lilith started attending the University of Britechester, and moved to San Myshuno. She finds it easier to blend in and hunt there, but she also loves the large number of Sims for other reasons. By chance, she met, and has been befriending, a spellcaster named Emilia.
I'm friends with the monster that's under my bed,
Get along with the voices inside my head,
You're trying to save me, stop holding your breath;
And you think I'm crazy, yeah, you think I'm crazy;
well that's not fair.