Trying to find a Doctor Who fanfic

HALP. There's a Who fanfic that I want to recommend to a friend who is watching for the first time and just got to the end of Donna's arc. It's total Donna headcanon for me, and I remember the story very vividly ... except what it was called or who wrote it. *facepalm*

( Spoilers for the end of Series 4 and BIG spoilers for the story in question (basically the whole plot - it isn't a long story) )

Does this ring any bells with anyone?

ETA: Also, as black_raven135 pointed out in comments - does anyone know if there is a Doctor Who ficfinders community? I'm not in the fandom enough to know.

FOUND! (By the author) It is The Road Taken by rheanna. And it is wonderful. :)