Ainz is an undead character, and his emotion suppression passive skill calms any strong human emotions.

While he retains his human memories, he prioritizes the safety and prosperity of Nazarick above all else. He is willing to commit atrocities if it benefits his guild, making him a villain protagonist or at least morally ambiguous, operating on a logic of "might makes right."

World Items are the most powerful artifacts from YGGDRASIL, capable of breaking the game's rules.

There are only 200 in existence, and the "Twenty" are even stronger, able to delete accounts or alter reality. Nazarick possesses the most World Items of any guild (11 total), giving them a massive strategic advantage.

In the final moments before the YGGDRASIL servers shut down, Ainz (on a whim) changed Albedo's flavor text from "She is a bitch" to "She is deeply in love with Momonga."

This small prank had massive consequences in the New World, as it made the Overseer of the Guardians obsessively loyal and romantically attached to him.

This is the central mystery Ainz investigates.

History suggests that "Gods" or powerful beings appeared every 100 years (like the Six Great Gods or the Eight Greed Kings), implying that other YGGDRASIL players have arrived in the past. Ainz acts cautiously to avoid conflict with potential high-level player threats.

Initially, Ainz's goal was simply to survive and find his former guildmates.

However, due to misunderstandings (mostly by Demiurge), the goal shifted to World Domination. Ainz plays along to maintain his image as the supreme ruler, inadvertently building a terrifying Sorcerer Kingdom.