Originally Posted by
Anarion
I think there's a bit of a difference. In LotR, they suffer and the world looks bleak, but at some level you always know they're going to destroy that ring. From the moment of the pledge at the Council of Elrond, that strength and that purpose drive the story.
Now, I haven't read your story, but I think that a lot of dark pony fanfiction, in general tends to spend more time reveling in the suffering. Readers get upset because the ponies are in such a happy world and many authors seem to delight in making them suffer and be miserable, and there's always the possibility of a story having a Hamlet style ending. So people get a little antsy when they see a fanfic labeled dark because it doesn't have that sense of pervading hope that keeps your head up when you're reading LotR.