The Simi, Charonte demon for "baby", is Acheron's demon daughter. She first appears right after Acheron is brough back to life as a God. When one of Acheron's mother gave her to him to care for, she was three thousand years old, the equivalent three in Charonte demon years. She calls him her "Akri", Charonte for "master". She can also turn into a multi-colored dragon tattoo, and reside on Acheron's body. In her demon form she has red and white marble skin like her mother Xiamara.
Artemis calls Simi 'It' and Simi talks in third person like "Simi" or "The Simi".