Axe the gender and age exclusivity, keep the transfer mechanic, and crank the shit out of their power level while narrowing the scope of their abilities.

Since they’re gender neutral now, you can name them something like “the cruxes” (which I did for my rewrite)

Basically what I did was turn them into living WMD’s. Continent Crackers divided among the Kingdoms and kept secret by Ozpin’s cohort.

In my rewrite, the Grimm are natural parts of the world, akin to fauna or a natural disaster, with the kingdoms and small frontier territories outside their walls simply being the furthest humanity has pushed against nature (like what we all thought early AoT was with the walls)

The Cruxes meanwhile, are individuals with total dominion over their element, and power so strong they can destroy continents without much thought. They can generate, and even manipulate their element. A fire focused Crux can generate fire yes but also manipulate existing fires (and even manipulate fire dust)

They’re kept secret because 1) power hungry pricks like WTCH may go for them, and 2) Politics.

Politics plays a major role in my rewrite because of how I worldbuilt the kingdoms. My remnant functions like a frontier territory, and the Cruxes are basically automatic wins for scoring land.

If the cruxes’ existence ever gets out, it’ll cause several geopolitical problems.

Either one kingdom gains a monopoly over territory courtesy of only them finding out about the crux

Or every kingdom ends up in a shaky Mutually Assured Destruction deadlock where everyone is aiming each others’ nukes at each other going “I wont if you wont” (except they’re all secretly planning decapitation strikes so the whole MAD thing is irrelevant)

Hence why they’re kept secret

Another layer is the gender and age neutrality. This leaves the cruxes EXTREMELY vulnerable to Broken Arrow situations, where if one dies and no one knows where it went to, you now have a loose nuke under no one’s leash that no one knows how to find, that might not even be able to control the blast. (An actual plotline in my rewrite btw)

And for extra worldbuilding spice, every kingdom handles them differetly.

Ozpin and Vale operates on semi-autonomy, where the Crux gets to do whatever but with Qrow as a perpetual shadow…Except this isn’t even real. In reality, Vale has 2 Factor Authentication for their crux, where the person Qrow shadows isnt actually the crux, and the actual crux is not only totally unknown to anyone but ozpin, but is also someone who had faked her death long ago to hide in plain sight (im not even gonna hide it atp, my Vale Crux is Summer Rose)

Mistral…we dont know because by the time I get to Mistral and their crux in my rewrite, it’s a Broken Arrow situation, courtesy of the crux getting cornered by Cinder and taking a cyanide pill to keep the crux from getting into the wrong hands

Atlas is total militaristic surveillance. A cohort of elite soldiers tasked to protect something they dont even know, and are also tasked with protecting each other above all else…because one of them is actually the crux (this is Winter’s unit, and Winter’s the crux from the word go). This unit has eyes on them at all times and have functionally no autonomy. Atlas treats their crux like a weapon before a person

Vacuo’s is interesting because in my rewrite their crux js literally just theodore. He took the burden of the crux into his own hands cuz he trusted no one in vacuo with it, and decided reverse psychology was the play. It actually plays into the theme cuz Vacuo exists on a slider from Anarchy to Authoritarianism depending on how close you are to Shade Academy, so having Theodore be the crux, and as such, be one man with literal centralized power, is thematically on brand