Help finding old Dr. Who fic

Hi I hope someone can help me find this fic. It was about the Doctor being turned into a dalek. It was from the perspective of Rose after doomsday, who finds a dalek and doesn’t know it’s the doctor. I think it turned out it was just the Doctors brain inside the dalek and he regenerated at the end of the fic. Pretty sure it was an alternate doctor.

This would have been written pre-2010, set after Doomsday, not Journeys End.