Ralsei just shows up and claims he's a prince and the third hero, even implying he was created purely to be the third hero
>COPIES ARE MONOCHROME,
>BUT YOU COLORED EACH OF US IN WITH CARE.
>There are crayons in the drawer. Their labels have long faded, and there's no green.
What if Kris or The Knight literally just made up Ralsei themselves as a copy of Asriel that they then colored in with green?