While I'm not a fan of Once Upon a Time, I do keep tabs on it and, I'm not sure if anyone agrees, but I think the series is more of a darker version of Kingdom Hearts...without travelling to many worlds in gummiships and there aren't any Keyblades either, and the fairytale stories are pretty much based on both Disney and the original fairytale stories.
But still, the Light vs Darkness thing is really catching on big time and it is similiar to both Kingdom Hearts franchise and some of the traitional Final Fantasy games, and Sailor Moon and Cardcaptors and ect.
Wonder what the last two episodes are gonna be like and how it will end that would lead up to season 6?
(Spoilers here)
Come to think of it, I think I recall that Walt Disney was mentioned in this back in season 4. So, maybe they'll place in Mickey Mouse next?(I doubt it, but hey, it's kinda turning out to be the Kingdom Keepers novel series)