I'm talking about what she's been doing for years, even before my MC's were born. What drives her, how she got there..., this is the type of stuff I'm worried about. She (let's call her "Sue)'s had plans , & she's gone about a certain way to make them come true. She's gone from a decent, but ambitious person, to an evil, ambitious person, she's manipulated others, including major supporting characters. One of these supporting characters (let's call her Jane) has, in turn, tried to manipulate the MC. What Jane's done is on-screen, but hidden because it didn't work. However, the attempt was very important to her motivation in the story, as well as to Sue, who in turn, would have used it against Jane. But Sue doesn't reveal herself as the big bad until the climax, and only right before that does my MC figure out that Jane is using him (although he still won't know the details). I think I'm okay w/ Jane's part being exposed, it's the background on Sue that I would have problems divulging without exposition.
Is that more clear on what type of thing I'm talking about?