Xerberos was another old god loyal to Celeste until he casted him aside and took the spotlight for himself. He followed Celesteh to war hunting down the old gods one by one. 

Xerberos was especially skilled in exhausting them by bleeding, he was smaller than the other gods but fast and agile. And when they were exhausted, his brother Celeste would come to finish them off with his sword and take their head back to Citadel as bounty. 

This Xerberos did not mind first as he was fiercely loyal to him. But when all the gods were dead, their bodies were trapped in a prison dimension, hell, so they would not be reborn; Celesteh kicked Xerberos into the dimension gate and sealed the gates after him so he would protect the dead bodies of the gods, remaining as the only god in power.