to my understanding Pantheon is the next champion up for a VGU. And I know that many people dont like that Atreus was subsumed by the Aspect of War (although I like that it does that for reasons)
so as a solution that's likely way too late, maybe the story can instead have Atreus be one of the few people strong enough of will to keep his identity.
from there, the story is a struggle of atreus bonding with Pantheon and trying to reach a sort of symbiosis like the other aspects have accomplished. the gameplay could be reflect this in some way too, though I dont know how.
I'm sorry if this is too derivative of Kayne and Rhaast, though this conflict would be one that's more beneficial to both of them than detrimental. I hope its found interesting