Appearance
The Demon Queen & King
The Demon Queen is a human from 300 years before the official discovery of necromancy. Unlike later necromancers who shared the discovery and ushered in an age of super magecraft, she lived in an age where witches were feared and shunned. She ended up hiding her secrets and pursued all her research privately.
This woman was old and wealthy, and had a husband who died young who she wanted to revive. Eventually, she did succeed in reviving him, by animating his corpse with a demon soul. Of course this soul has nothing to do with who he was originally, and his brain had long since been destroyed by decay. But through judicious training, she managed to teach him what her husband was like and was partially satisfied with her animated doll.
But still believing that the problem was that she didn't find the right soul, rather than understanding that humans have no souls, she sought the source of souls, Annilm. She opened the portal to Annilm and immersed herself within with her husband, and tested many souls by bringing them into her own body.
She disappeared from the human world, moved permanently. This experimentation eventually destroyed her mind, and she became integrated into the soul of Annilm, as an Aspect of Annilm. She became the Demon Queen, and her husband became the Demon King.
Demon Queen Personality
Aside on Souls
Souls are a force of nature, non-sentient. The demonic forms they take on are an afterimage of the Demon Queen's hatred for the humans who persecuted her and called her a witch.
Eventually the Demon Queen's will seeped into all the souls and gave them instincts, however the demons are still not capable of reason. Demon souls are immortal, indestructible energies that can be harnessed by the technology of necromancy.
You can choose to say that you feel sympathy for the demons, but they will just call you out for inappropriately anthropomorphizing them.