So far, all I know about Ydwin's intriguing backstory is what I've read on the internet - nothing in game. I've taken her to the animancy teleport quest atop the spire, and through the Beast of Winter, but it doesn't come up. Since she's a sidekick, you can't really talk to her either.
Did I miss something? Or is there a specific situation where you can find out more about her?