Challenge Overlord X Invincible (Image Comic)
What if Ainz reborn as Mark/or Mark's twin brother, making him a Viltrumite.
Unlike in the original story, Ainz will awaken his power as Viltrumite at a young age, and along with that, he realized that he gained access to his Yggdrasil power and equipment. Will you make Ainz's into a hero or a conqueror up to you.
Example if he is conqueror:
As Viltrumite have no defense against Magic Ainz will manipulate his father using Mind Control once he knows his true goal, and will use Nolan as a mean to enter Vitrumite Rank, and become their leader. Ainz will then take the billion Viltrumite corpse that makes the ring on the Viltrumite Planet to make invincible Undead under his command.
As hero:
Ainz could have wanted to simply protect the planet as a mean to protect the environment because Blue Planet (His guild friend) loves natu. He might agree with the whole conquering thing, but he will disagree with Viltrumite's unnecessary violence. He will join guardian of the globe to help protect Earth betraying his father.