Deimos

It is said that before the start of the Dark Age, Ares drew his feelings of Fear, Panic, terror, and dread and cut them out of his soul so that he could be a fearless warrior. Little did he know that these parts of him would eventually be merged into two beings of Panic and Fear.
These beings would eventually be given names by those who encountered them initially, soldiers during the Dark Age fighting in the God War as they confronted them. The second would be named Deimos, the name of fear-given form.
From the accounts of the Dark Ages, it is said that this being would follow closely in the wake of its "sibling" Phobos. Those who first encountered the being now known as Deimos describe it as a humanoid being that would appear in soldiers' camps before a battle. It was reaping destruction and fear at night before disappearing, only to join its "sibling" amid the conflict, fighting alongside it. It is said that the fear it sowed in those that fought in the God War was crippling and led to many a hero's death or disappearance; it was said to bring out the worst fears in a person and make them a reality. Combined with its "sibling," this power would mark several horrific scenes of the Dark Age that the accounts refuse to go into detail about.
When the Divine Barrier was erected, it is believed that this being was pushed behind the barrier alongside its sibling. However, there are whispers of a being of great fear and scenes of horror and fear-inducing nightmares that are said to still be prevalent today, with no one knowing their cause.