One Fic to Share with a Newbie

[tinturtle]

If you had to choose one Pros fic to share with someone who had never read fanfic before, which one would you choose? What Pros fic that you have read do you think best showcases what fanfic can be?

(Assume the hypothetical newbie is familiar with the show. Optionally, you may also assume they are receptive to slash.)