The Vanir lived in Vanaheim, but that didn't mean Vanaheim belonged to the Vanir.
It sounded convoluted, but it was the truth.
Simply put, the Vanir had once been the sister race of the Aesir. The Vanir and Aesir had once been one, intermarrying with each other.
But later, the Vanir awakened.
Long ago, after the Vanir had helped Odin of the Aesir unify the World Tree, the passage of time gradually led the Vanir to discover something they had never noticed before.
The Aesir had changed.
After ruling the World Tree, the Aesir's way of life grew increasingly extravagant. The Vanir could no longer stand it. They even found it difficult to see what meaning there was in building that golden city.
And so, the Vanir attained enlightenment.
What was power?
What was war?
What was conflict?
Without a doubt, the Vanir eventually realized one thing: no castle or statue, no power or conflict, could compare with the most noble thing of all—life.
After failing to persuade Odin, the Vanir chose to return to Vanaheim. They abandoned their towering castles, reined in their swelling ambitions, withdrew into the mountains and forests, and praised the simplicity of the old-fashioned way of life. They no longer pursued the increasingly extravagant lifestyle of the Aesir.
And even...
The Vanir returned to their original ideals. They no longer treated Vanaheim as the territory of a god race. The Vanir welcomed every peace-loving living being, so long as they followed the rules established by the Vanir.
"Under Odin's rule, which appeared benevolent on the surface but was actually centered on violence, some of the World Tree's inhabitants fled to Vanaheim. They settled there under the protection of the Vanir. Those people are the ones who have risen up today."
"...Interesting."
"Huh?"
"I don't know