Eris, The Grieving Monarch

Eris was the first living creature brought into life by the elementals. She is a wolf beastkin, but of a different type. Modern day beastkin have large ears on the side of their head, hers are much smaller and more wolflike. Eris took mantle of Monarch after others were created, feeling it was her right to lead them. As with all things, her reign was temporary. As more land was shaped, a large flood occurred, destroying her kingdom and wiping out her people. She was the only survivor by a stroke of fate. When the waters receded, she began to grieve. Her grieving was of such emotion, that a dark mist the same deep purple of her eyes spread from her. She did not notice herself gaining strength, or not requiring food or water. She grieved for exactly 3 years, and when it was over, she had become the first demon.
As she wanders the lands, she is under the delusion that her people were killed in combat. She seeks to avenge her people, long forgotten the truth of their demise. In her past, she used an axe, but she has long since lost it. Now she fights with various weapons that she makes by crystallizing the very mist that is created by her presence.
Eris is responsible for the creation of most other demons. As Eris existed, the demon's mist that accumulated eventually coalesced into its own plane. Because Eris was responsible for its creation, Every time a demon birthed from that plane dies, Eris gains a small fraction of its strength. While this fraction is typically inconsequential, over one thousand years, it adds up.