psychicscubadiver's The Dresden Fillies (which crosses over the generally light G4 My Little Pony (i.e., Friendship is Magic) with the semi-noirish wizard detective story The Dresden Files ) works way better than it has any right to. The second one in particular was a novel-length rendition that captured (Dresden Files author) Jim Butcher's writing style so well that it felt practically indistinguishable from the real thing, ponies notwithstanding.

It also makes the little things in the series make so much more sense. Like, remember in A Canterlot Wedding how shocked everyone is that the Chrysalis managed to floor Celestia? In this fic, is's because she was almost killed in an attack with some serious negative juju that Harry had to basically surgically remover from her. There's a third chapter where the Mane 6 go all Equestria Girls and visit Harry in Chicago, but it's been in development hell for the last 8 years.