Midna is probably still the most unsuspecting character from the Legend of Zelda cast to be included in Koei Tecmo's upcoming franchise mash-up, but Fi must be a close second.
Last seen as Link's assistant 2011's The Legend of Zelda: Skyward Sword, Fi is some manner of spirit or goddess that lives inside, or is the sword... or something like that. Apparently she has been woken up again for Hyrule Warriors, and by the looks of this trailer has a much more hands-on role in this game.
Hyrule Warriors is due exclusively on Wii U in Australia on September 20th, about a month after the game's local Japanese launch.