Maybe she pursues the adventure & intrigue as a burden that was passed on to her by a deceased relative. Her uncle, cousin, brother, etc passed away, and she was contacted shortly afterwards. Maybe it's something that only she (as a direct descendant of such-and-such) can do.
Or perhaps she does have children, but they were placed in a boarding school by this mysterious contact. If she doesn't work for them, she may never see her children again. And of course, if she tells her husband or steps out of line, they may just . . . disappear.
She started out as a minor filler character, she was supposed to add a little flavour to a ball. That first thing sounds like she will take up a lot of room. While I do want her to become a major player at some point, I think she's a bit too proper to go around dungeoneering, if that's what you meant? Sorta Indiana Jones kind of thing. I should also mention that she's 39.
The boarding school idea is interesting. Even though she is seemingly without enemies, I suppose she would need some, in order to spice things up. It would also get her a personal plot hook. But having her children in the hands of some mysterious stranger while she's out galavanting without a care in the world seems kind of odd. Unless that's also a ploy... Ooooh, maybe I can tie it to the templars! Yeah, that makes sense...
I think you already did a fine job of painting her desires/needs...She yearns for excitement and intrigue in her life. That in and of itself is a powerful driver.
Maybe its because I watch too much BBC, but she seems a classic archetype, who secretly and ingeniously murders/ruins/destroys anyone who gets in her, or her husband's way (he remains clueless), while maintaining her veneer. As Dossta mentions, she also sounds the type who would do ANYTHING to make sure her children survive and thrive.
Perhaps, with her having the ear of the queen and a princess, what she really wants is POWER, but goes about acquiring it in a complicated and convoluted way, slowly strumming the myriad strands of her spider-web of intrigue.
1) Yeah, but she's allready getting her fill from working with the information broker. And she's too old to be doing anything more dramatic.
2) You make her sound evil and ruthless. I want her to be a character that can be trusted. But of course, she could seemingly be one way and yet...hohoho...Oh, I'm a sucker for evil chars, that much is true. Maybe she worships Lolth... Nah, that would be taking things too far.
I think it practically jumped out at me after I read the line "She loves dashing rogues types...."
Ugh, typo. Fixed.