With all this talk of Dr. Begabank experimenting with the Devil Fruits, not to mention Merry aquiring a "ghost", I wouldn't be surprised if the sea itself also had a "ghost" or "soul"; if this is the case, the sea isn't causing Devil Fruit users paralysis due to chemistry but rather on a metaphysical level.
If this is the case, could the sea have a "chosen" Devil Fruit, id est, a demon the sea likes? if so, would Luffy as Pirate King be this "chosen" Devil Fruit? If acceptance by the sea is possible, could it also be a part of the One Piece?