Second, how long has it been since I recced a fic? It's been ages since I even read one! (My poor attention span, movies and fics are just too much for you these days.) I'm not even in this fandom, I never even saw the movie (movies?). That must be the sign of a good fic -- it's a great read even if you don't know the source material.
Gone Is My Past by cyerus (Sherlock Holmes fandom). The prompt the story was based on is "John is an Army bomb detection dog who has been turned into a human."
It's so sad and heartbreaking and believable (odd thing to say about a story where a dog turns into a person). The love in it was just so... wonderful. (Love-love, not slashy love. It does have a PG-13 rating, though I'm not sure why.)
I'm sitting here grinning while thinking about it. I love the ending, I endlessly love the characters. I now want to see the movie, just to see more of them. And, once I post this, I shall be poking through the author's LJ looking for more to read. :D
Edit: Wow. Other fics by this person? Just as good!