Zatch Bell crossover
fem-you are dating Fluttershy but she has gone missing you believe that she has be kidnapped by Mamoto Z to be one of the mind-controlled book keepers, so you join up with the show's protagonists to fight Mamoto Z and rescue all of the book keepers.
oh and Li-en is a homophobic but you talk her out of it
I've had variations of this story running through my head for probably over a month now, and I finally got myself to actually write this