Why Norse Gods and Giants Hated Each Other That Much?
If you have completed Norse mythology, you may know that the end of Norse mythology was marked with Ragnarok the war of gods and giants. Although no sources mentioned the exact reasons what made the hatred between gods and giants, we all have our own way of thinking. Many assume that it was because Loki wanted to dethrone Odin, Loki wanted to make gods pay for what they had done to Loki's family, etc. My personal viewpoint is this hatred was rooted right from the beginning of the cosmos.
For a long time, we often call Loki "the one who pulled the trigger". But Loki, in my viewpoint, was just a trigger. This trigger was pulled by Ymir the ancient giant. Bullets were giants like Fenrir, Hel, Jormungandr, Nidhogg, etc.
So my opinion is, because of Ymir, gods and giants hated each other that much.
Where this hatred began though?
Before Norse Pantheon, there was nothing in the cosmos. There were two realms, instead of nine. Muspelheim land of lava and Niflheim land of ice were two of them. And there was one Ginnungagap "Mighty Gap".
Muspelheim in Norse mythology
When the lava from Muspelheim met the ice from Niflheim in the Mighty Gap, it caused the Norse Big Bang. After the explosion, there came the first being in the cosmos - Ymir the giant.
But Ymir was not alone in the cosmos. There was also a cow named Audumbla. Ymir drank the milk from the cow. Audumbla the cow licked the ice for living. And the lick of the cow revealed the third being to the cosmos - Buri the First God who was also the grandfather of Odin.
The sweat of Ymir became the traces of giant. Meanwhile, Buri had a son named Borr who was the father of Odin. The mother of Odin was Brestla who was a mighty frost giantess. That's to say, Odin was a mixed god.
Odin had two more brothers, Vili and Ve. They grew up to become the new generation of gods at that time.
Ymir the giant and Odin's brothers in Norse mythology
Until one day, the brothers decided to do something which made the whole cosmos change. They conspired to kill Ymir the giant.
The triad, Odin, Vili, and Ve was the strongest ally ever in Norse mythology. They managed to kill the giant with ease. And the gods decided that they would use the corpse of Ymir to fashion the world.
Scholars have been debating what world Odin and his brothers created. But the majority favored the idea that the Vikings fashioned Midgard, or Planet Earth. They used the hair of Ymir to make forest, teeth and bones for cliffs and mountains, blood for the oceans, etc. The worms from the dead body of Ymir became the dwarves who lived in the Svartalfheim.
We don't know why Odin's brothers decided to kill Ymir. But I assume that the hatred between the two tribes began right at the moment Odin and his brothers put an end to the life of Ymir. And blood for blood, that's a rule. Odin was killed by the offspring of Ymir and the Norse Pantheon collapsed.
Overall, the hatred between the two strongest clans began from the beginning of the cosmos - the death of Ymir. When Odin and his brothers managed to kill the ancient giant, they also created the disaster of Ragnarok as well. That's why I believe Loki was not the one who pulled the trigger. Instead, it was the death of Ymir and the gods themselves.