@Riot: How often will you be introducing non-Champion characters into the story?

You can't have only playable characters as your cast. There needs to be outside characters who are in the background, are fairly important, but either can't fight or don't qualify as Champion material.

For instance: a merchant like... http://img2.wikia.nocookie.net/__cb20130509153335/fireemblem/images/3/3f/Anna_FE13_Artwork.png
XD (Fire Emblem Awakening is such an awesome game.)

Said peddler/merchant could be a friend of Sivir's who buys most of the valuables and such that the Battle Mistress finds on her excursions. But if you asked her to fight in a League match? "No way!"

Or perhaps a nun/priest in Demacia who, obviously, does no fighting, but provides spiritual support and guidance to characters like Vayne, Lucian, Lux, etc.

Seeing characters like this occasionally in the lore would reduce the whole "Smash Bros." feel of the story and actually add some life into Runeterra.