Lost Girl is a Canadian television crime/supernatural drama show featuring Anna Silk as Bo, a succubus who is introduced to a hidden world of creatures called the Fae who appear human (for the most part) but who are much more. Bo was raised by humans, unaware of her nature and suffering from the fact that anyone she is intimate with would be drained of their life. After rescuing Kenzi, a Russian transient con artist, Bo is discovered by two Fae who work for the local police department. Surprised that she was raised apart from the Fae, the two detectives Dylan and Hale bring her into the Fae community. The Fae are divided between Light and Dark, not necessarily Good and Evil, but more Lawful and Chaotic. All Fae feed directly or indirectly on humans, but as one Light Fae put it, "we're like Native Americans. We respect our prey."
Bo refuses to become part of either society, since both are bound by strict codes of conduct, but instead becomes a rare neutral figure. Her ability to mingle with both Light and Dark Fae make her a unique figure in society and she ends up frequently taking on problems no one else can.
In addition to Kenzi, Hale, and Dyson (her werewolf love interest), Bo is also helped by Trick, the owner of a Fae-only pub, and Lauren, a human doctor and servant to the Light Fae (and also a love interest for the bi-sexual Bo).
So to summarize, you have in Lost Girl a sort of sexpot-Buffy the Vampire Slayer meets World of Darkness. It's lightweight fare, fun and easily qualifying as a guilty pleasure. The show is pretty PG-13 with a lot of simulated sex and near-nudity, not to mention a lot of off-color humor.
My biggest problem with the show? Anna Silk is a striking person physically, but is outshone in any scene that involves another member of the cast, especially her sidekick Kenzi, played by Ksenia Solo. Bo's transformation from "lost girl" to "tough girl with a medieval arsenal" seems almost too quick. And finally Lauren, the alternative romantic angle for Bo, is consistently whiny and lacks appeal.
Now it would be very, very easy to game this. You could use the Buffy/Angel/Ghosts of Albion rules and be ready to go practically out of the box. While the Fae society is very vague in its description, it appears that regions have local leaders, Light and Dark, and so you could create your own parallel monarchies in another metropolitan area and have the PC's be other Fae or human sidekicks that have decided to follow Bo's lead and reject the Fae social order (there's even a weird cursed tribe out there, not to mention mercenaries, so Bo isn't all that unusual as she seems at the beginning). Everyone in the show has secrets to go with their extensive personal histories, and half the plot is uncovering all those hidden elements (the other half being taking on sketchy jobs for Light and Dark Fae).
Lost Girl is on Netflix right now, and worth checking out.