This is tough; there's not a whole lot; certainly not as much as there are doujinshi. But there are some:
Basically everything by Iced Fairy is worth reading, IMO, but at least take a look at Gensoukyo Shorts for some unusual couples:
(Even the stuff that has Marisa. Maybe even especially the stuff that has Marisa.)
Taiyakisoba has some decent stuff: https://www.fanfiction.net/u/5332266/taiyakisoba
/UnmovingGreatLibrary Has a bunch, especially Teeth and Claws: https://www.fanfiction.net/u/4970666
This was silly: https://www.fanfiction.net/s/7301323/1/
This is slowly WIP, but unusual enough to be interesting: https://www.fanfiction.net/s/10105236/1/>>1781310
This. This is what impeccable taste looks like.