Not many people know that Nier is the older brother of the Child of Observation, and he intends to keep it that way. He protected his sibling when they were both young Stygians, and watched the Prince attain greater power than he ever could. When the Prince formed the Starbound Court, he offered Nier a place amongst the stars. However, Nier felt that his flames of vengeance were unfit for the Prince's grand visions, and declined the position of nobility. Since then, their paths have diverged.

Nier made a name for himself during eras of widespread conflict, working as a mercenary. He was known as a vicious and cold-blooded hunter, who never forgets a grudge or a debt to be repaid. He once sent three Stygians who betrayed him into the Labyrinth to a fate worse than oblivion... at least, that's what the rumors say. He lives a solitary existence and doesn't care about others' opinions, which makes him really hard to approach.

Currently, he has retreated from the public eye and spends most of his time brooding in his Kingdom. The unexpected arrival of a shattered star has changed him a little bit, even if he tries to deny it. (Unfortunately for him, he's a tsundere.) Caring for another person is difficult, but he's not the type to give up easily.