Odin, Vili and Ve are brothers. It is said that these 3 gods were the one that made the world. Though, Odin seems to be the most famous one among the 3 because, he was the eldest, definitely the strongest and he ruled Asgard.
They made earth by killing Ymir. Ymir was a hermaphroditic frost giant and was the first of its kind. He can reproduce asexually and could make more giants from just his sweat. Which makes sense because he was literally made from ice.
Then after some time, the 3 brother’s decided to kill Ymir. Because apparently Ymir was turning evil. They then succeeded in slaying the giant for good. They even made a “trophy” out of killing Ymir by dragging the corpse to the centre of the primordial void and started crafting earth using the corpse.
Ymir’s flesh was the basis of the earth. His bones became rocks and hills, his hair turned into plants. His blood formed the sea. Then his skull became the sky and the clouds were made from his brain. Then finally his brows or eyelashes became Midgard where all the dwarves, elves, humans and the like lived in.
From the slay, we could assume that the brother’s bonds were quite tight. They even wore somewhat matching metal armor where Odin wore gold, Vili wore silver while Ve who was the youngest, wore bronze.
But Ve challenged Odin to a duel one day and thus he excepted. Well since Odin is more famous than Ve, its no surprise that Ve lost.
As punishment for his insolence, Ve was banished to the underworld and was stripped of his armor as punishment. But, little did Odin know, Ve shagged his wife and as a result, without Odin knowing, has a son called Baldr which he thought was his own.
Then came Ragnarok which was the end of the world, well I guess recreation came soon after. Anyways, during Ragnarok, Fenrir who was a giant wolf and was the son of Loki, went on a rampage and killed a few gods here and there.
This included Odin who he swallowed. Vili, at the sight of Odin being swallowed, lost all hope and sacrificed himself to Fenrir. While Ve who was called back from the underworld to help fight, ran away and later also died either by Fenrir or by mistake when an elf mistook him for someone else.
So the 3 brother’s were killed during Ragnarok just like most of the other gods in the Norse Mythology.