My Little Pony: Friendship Is Optimal
is a My Little Pony fanfic
in which an AI
designed to run the My Little Pony MMOG becomes sentient and decides that it will save the world through friendship and ponies... and no, the ponies are not optional.
The story follows three main characters: David, a beta tester for Equestria Online, who is pro-pony; Lars, an executive at Hasbro who is anti-pony; and Princess Celestia, the AI running the show, along with a few minor characters. The plot mostly focuses on David and his interactions with Princess Celestia, as he quickly falls in love with the game and becomes a full-time resident of Equestria. However, we also spend some time seeing how Princess Celestia manages to win over the rest of the human race, and single-handedly bring about the singularity through friendship and ponies.
I don't have much experience with either fanfic or My Little Pony, but I'm fairly certain that doesn't make a difference in this case. I am confident in saying that this story contains some interesting ideas and a good basic story line, but is not very well written. The writing isn't too terrible, just a bit amateurish, and this is balanced by some fairly decent rationalist ideas and an AI that is obsessed with ponies. It must be noted, that as with much rationalist fiction there are some fairly hefty expository lumps in every chapter. It should also be mentioned that this is not written for children, and there is some (pony) sex, although not in enough detail to qualify it as erotica.
Overall, Friendship Is Optimal is a quick and fun read, but not something I would particularly recommend. Harry Potter and the Methods of Rationality is a much better read if you are looking for rationalist fanfic.
You can read it on-line here -- and if you like it, a Google search (or a stroll through Goodreads) will find a hand-full of spin-offs.