Searching for a doctor who fic
So in this fic (which I read on fanfiction.net) theres this girl thats really super humanly smart (because I'm pretty sure she used to be a time lady and she used the chameleon arch or something like that) and the doctor wants to meet her because apparently later on in her life she just disappears and no one knows what happened to her(the night she disappeared there was a ton of blood in her bathroom). Both her parents died in a car crash when they were on their way to her violin recital I believe. She ends up traveling with the doctor and Rose, and she and the doctor fall in love and have a kid who happens to be Jack Harkness. I think at one point she falls down an elevator shaft and Jack saves her, and also she gets kidnapped later in the story and the 11th doctor has to save her if I remember correctly. That's really all I remember and I've been looking for it for a while.