Three new ponies arrive in Ponyville, or maybe two were already there. They live in a large mansion together and drink a lot of wine. Their life is not entirely uneventful.
There are ghosts and vampires, sordid pasts and crossed destinies, and at the end of the day lessons may be learned but scars are deep and at the end of one's life one is not left with an overwhelming joy but merely contentment.
I am sort of proud of my characterization of the Mane Six in the 2nd chapter, so maybe just skim the first chapter to orient yourself and read that instead.

Ursula is a fat pony. She does not have a long life. However, she has a long and productive death, and her namesake alters the world forever. I am not sure what to add here without ruining the plot, so readers who venture beyond this point beware! ... The story involves Ursula, a "maggot" born from the body of Ursula, who enters the world of ponies, eventually learning the value of friendship, and even love.