Eònan
Eònan's history is lost even to him. Small snippets, memories and faces remain ingrained in his head and the only source of his being comes from his mistress Favashi.
Millenia ago, Eònan was a storied swordsman and hero of his people. His skills were legendary and through his military acumen and skill as a warrior the country he served thrived. With each victory, with each battle, stories of him spread and while the reputation allowed great morale and success for his people, it drew the attention of more malevolent beings.
In times gone by his, Kingdom faced an enemy far greater than themselves and they turned to Eònan to save them yet again. With the odds stacked against them, Eònan turned to more eldritch and ancient means to save his people. He pleaded with the Gods, he pleaded with anyone who might help him. Unfortunately for him, his pleas and reputation reached the ears of the Fae of War.
She ensured the survival of his people, victory after victory, he led the armies of his Kingdom through great battles and tremendously long odds. Yet when his people needed him most, he vanished. Favashi, ever cruel, snatched him from the realms of men on the cusp of the final climactic battle and his men - disheartened by his retreat and fleeing - were routed. His Kingdom succumbed to the greater power and was lost to the tides of history.
The following millennia passed as a blur. His mind, his personality, his form ever shaped by the will of his mistress. She commands him and he is powerless to resist. His soul remains in her possession and Eònan finds himself unable to resist the call to serve Favashi.
For all intents and purposes, he is a mere human in peak physical condition, yet his skill with a sword has been honed for untold lifetimes. Equally, Favashi is unwilling to relinquish control of such a useful asset and, as such, his body regenerates from even the most mortal of wounds. Death refuses to welcome him, not until Favashi wills it or she too perishes.