Since Master Yi is from Ionia and Katarina is from Noxus it would be pretty interesting and nice story if we ship those two champions. There could be another war between Noxus and Ionia which has been stopped in the middle of a fight by a great typhoon which takes Kata and Yi to another unknown land full of unknown creatures. Left alone,Katarina and Yi are realizing that they will have to work together if they want to survive and find a way to go back home. How time passes they fall in love with each other meanwhile war between Noxus and Ionia is still on! When Katarina and Yi finally find way home,together they are stopping this great war.
(This was just an idea and a short story of course many details and things could come between in this all,also movie about this would be cool :D hope many of you will like this story and i hope it will be a part of their lore!)