I've never read a fic with Derek having a sister named Sophie. :S I'm personally not a fan of fics where writers choose to change the characters' names or add siblings to the family. Idk, just not my thing. (I can understand if it was before we knew Derek's sisters names, though. We learned Nancy and Kathleen in season 3. Amelia in season 3 of Private Practice [which coincides with season 6 of Grey's Anatomy], and Elizabeth in 9.)
|