The origin of the three-headed Chimera was said to be the same as the origin of the legendary Hydra and Cerberus, the Gatekeeper of the Gates leading to the Underworld.
They were considered monster siblings even though they looked very different. Their origin could be traced back to the time before the God's Era and it was said that the first ancient texts of the multi-headed monsters appeared around the same time the Colosseum had been constructed.
When Zayn read about this for the first time in the Archive of the Adventurer Hall he had been quite surprised.
There shouldn't have been monsters like this before the Realm Fusion. Only with the fusion of the realms did all kinds of monsters appear in this world.
But according to the ancient texts that didn't seem to be the entire truth either. Various texts of existing monsters had already been noted down long before the realms had fused.