Clone Wars series (SPOILERS)

[Murazor]

Though, given the EU's propensity to a) give every little character a huge backstory and b) screw things up royally, it may be a good thing I don't know more about Ventress.

As far as I remember, Ventress' background is as follows: she is the daughter of a couple of political leaders who were trying to bring peace to their homeworld (in a state of perpetual war and divided between competing warlords) and got killed for it when Ventress was still pretty young.

Later, a random wandering Jedi showed up, kind of adopted her (she seems to have been his padawan, despite the lack of official sanction) and together they tried to stop the war in Ventress' homeworld. Once again, the warlords decided that they didn't want this and had the Jedi killed, but Ventress somehow survived.

She blamed the Jedi Order for the death of her master (not sure if there were romantic implications there or not) and started to use the Dark Side. More or less at this point, Dooku met her when she assassinated one of the aforementioned warlords who had invited Dooku to a gladiatorial fight. After showing Ventress who was boss with a fat lot of Sith lightning, Dooku recruited her and sent her offworld to start killing Jedi and such.

[Darth Fanboy]

Though, given the EU's propensity to a) give every little character a huge backstory and b) screw things up royally, it may be a good thing I don't know more about Ventress.

Ventress' background is clarified quite well in the Clone Wars comics, you can look it up there if you like.

As far as I remember, Ventress' background is as follows: she is the daughter of a couple of political leaders who were trying to bring peace to their homeworld (in a state of perpetual war and divided between competing warlords) and got killed for it when Ventress was still pretty young.

Her parents were actually a pair of competing warlords, haven't read anything about them being peaceful.

Later, a random wandering Jedi showed up, kind of adopted her (she seems to have been his padawan, despite the lack of official sanction) and together they tried to stop the war in Ventress' homeworld. Once again, the warlords decided that they didn't want this and had the Jedi killed, but Ventress somehow survived.

Master Ky Narec, and you're correct in that she appeared to have been an unofficial Padawan. The Ex-Warlord who recounts the tale to Obi Wan notes that the plan to kill Ventress and Narec half-failed.

The pictoral account of her conquering Rattatak once and for all seems to indicate that she took full control of the world after she became Dooku's apprenticeas she is using her twin red lightsabers and has learned new techniques from "other off worlders".