Xiao is not this yaksha's true name, but a name given to him in the interests of his own protection.
Back in a younger, more naive time, a god had gotten a hold of Xiao's weakness and forced him to serve as their bloodhound, in which capacity he was forced to perform cruel and violent acts.
Many died at his hand, many hopes were crushed, and he was even forced into devouring his victims' dreams. As much as it pained him to do this, he was helpless to resist.
Finally, on the battlefield of the Archon War, Morax, the Geo Archon,[Note 2] had a fateful encounter with the yaksha's master.
The current state of the world has already revealed the results of that battle.
Rex Lapis liberated the yaksha and gave him the name "Xiao."
"In the fables of another land, the name Xiao is that of a spirit who encountered great suffering and hardship. He endured much suffering, as you have. Use this name from now on."