I would recommend reducing the amount of power the MCs have. Start them with either one power they have semi-control of or two powers they barely have control of. Then, as the story progresses, they could grow in their control of power, unlocking new powers and wresting greater control of their previous ones. Afte that, come up with an antagonist. Maybe the antagonist could be unaware of the MCs, then some sort of incident happens publicly with each of them and the antagonist starts to take action, sort of like the Black Riders from LOTR.
Other than that, I love the concept. Keep working hard!
My friend @iLewoArtist29 is an avid writer, so she'd probably have some pointers for you.