Fan Fic / Twilight's Dollhouse

Twilight's Dollhouse is a Dark Fic based on My Little Pony: Friendship Is Magic, written by Kaidan and available here.

The newly coronated Princess Twilight suffers an abrupt tragedy. Having lost two loved ones, she begins to question her own mortality, and that of her friends: AJ, Dash, Rarity, Pinkie, Fluttershy. And they are just the beginning. Twilight will live for thousands of years, so every pony she cares about, every pony she will ever care about, will die. She can barely handle the pain of one funeral, let alone the thought of hundreds of them. Twilight finds a clever way to ensure all of her friends never die. They can’t all be ageless alicorns, but they can all move into Twilight’s Dollhouse. Then they can be best friends forever.

The sequel, Twilight's Dollhouse II has recently begun, and Kaidan says that he has plans for further sequels.