I think you mentioned it already but selling your soul to the devil right? The devil's pact? Davy Jones as the actual sea devil and Imu is usurping/imitating that maybe as "Umi"? I wonder if Imu is meant to be Calypso too then?
Imagine like how you get powers from the devil fruits and thus the OP version of asking the devil to grant you powers but a more extreme version where you can tap into Davy Jones' power or something primordial/supernatural/fantastical or w/e, a literal godly power but like the Domi Reversi, it transforms you but maybe permanently or until it kills you ultimately? Kinda like how "the hero water" in Alabasta was meant to give you a massive power boost but would kill you ultimately afterwards?
I wonder about that "hero water" too, heh....One of the more interesting things about OP that often goes overlooked and forgotten...imagine if it was related to the fountain of youth or something equivalent of that in OP somehow? Id love to know what the inspirations of it were.
HMMMMM......
Ooooh, nice connection to the Hero Water.
Yeah, Davy Jones would be the Sea Devil here: we already know Spirits exist from both the Klabautermann and Film Red Lore.
And Brook, LOL.
Series is all about Inherited Will, too. Well, what happens when your Will actually surpasses death?
Davy Jones could very well be a Spirit/Demonic Entity at this point, not even mortal.
Teach's Darkness Fruit resembles Imu's powers a lot, IMO; I've been wondering if the Yami can make use of the Abyss.
Davy Jones and Imu having the same Evil Power as their source of strength is very interesting.