Soul Demons rarely took a physical form before they became Soul Overlords. They were mainly attached to humans or fierce beasts to reproduce and evolve. However, once they became Soul Overlords, the energy they had accumulated before would completely explode and coalesce into their physical bodies, which were also the true Soul Overlords' bodies.
Soul Thirteen had never wanted to expose his physical body. The main reason was that once exposed, his aura would leak out, and he would lose his mind and completely fall into the will of the Gluttony Soul Overlord, becoming a mindless existence whose only purpose was to eat.
This process would last for a long time, perhaps a year, perhaps ten thousand years. Only through the baptism of time would his raging will return to normal.
