Aeternus became the god of spirits and the gate keeper of Infernus after the god killers commanded him to make the realm for the lost mortal spirits. Angry that he was cast away from Divinus, Aeternus rules over Infernus with the hope to overthrow the gods. While he was told to provide peace to the spirits, he imprisons them and siphons their power for himself. Because the power isn't given in worship, the power causes a spiderweb of poison to spread across his skin. He will continue to decay until he can rule over Ertho once again.

The origin of the Witch Goddess is unknown. She existed before mortals were created. During the war between mortals, Imara saw the horrors that people could enact on each other. As she loved the mortals, it broke her heart to see them destroy each other. Worst of all, she saw the most evil mortals harm the defenseless: women and children. So, Imara took the women and children into the Mysticus Forest to protect them. While they lived there with her, she trained them in the arts of witchcraft. Over time, they became known as the first coven. Imara is, naturally, a protector, caregiver, and healer. In the mortal realm, she takes the form of a humble healer. In the spirit realm, she remains in her true form.

Milo is the adopted demigod son of Aeternus the god of the spirit realm. After his father, the god of War, traded him to Aeternus to save his mortal love from the spirit realm, Milo became Aeternus's servant and warrior. After Milo was left severely abused by Aeternus, Imara the goddess of witchcraft took him in and healed him. She tried to protect him as much as she could from Aeternus. She taught him in the skills of witchcraft, including apothecary skills, potion making, and the art of the warrior dance. Eventually, he became the main recruiter for the witch's warrior army.

Althea is the main character of The Witch's Warrior. She grew up in a cabin in the Mysticus Forest with her father who was a mortal soldier. As a child, he taught her how to read, how to fight, and how to survive. As the only mortals who lived in the Mysticus Forest, Althea made friends amongst the wandering spirits. One spirit, whom she calls Mother, helped her develop apothecary skills. Along with her warrior skills, Althea is adept in foraging the woods for medicinal ingredients, which is her favorite pastime along with reading.

The Witch's Warrior consists of three realms. Ertho is the realm for mortals. It is a mountainous land surrounded by ocean. On the coast, is a city called Illuminare--the City of Light. Outside the city walls is the Mysticus Forest. Mortals avoid it because it is believed that the entrance to Infernus, the realm of death, is there. Because of this, it is believed ghosts, witches, and dangerous monsters live there. Infernus is the realm of spirits. When the gods created mortals, they gave them a seed of their power, known as "god power". At that time, mortals could live forever as long as nothing happened to their physical forms. As time went on, conflict began between the mortals, and they soon went to war. The mortals could destroy their physical forms, but the seed of god power remained. Thus, spirits were forced to linger like ghosts in the outstretching woods. The god Aeternus created the realm of spirits, later known as the realm of death, for the spirits to rest. No live mortal has ever seen Infernus, except for the witches who serve the witch goddess Imara. Divinus is the realm of gods. The beings who give mortals life live about Mount Divinus. The kingdom above the clouds is not known to the mortals nor has anyone ever seen them. However, mortals known that the source of their power comes from the gods who live in Divinus, and they worship them.