A Mountain Within A Mountain.

Stelios tried and failed to possess a clone of Legion so her failure is not special. But he considers her to be worse than being foolish for attempting it at all. She is a clown that isn't funny who then decided to do something dangerous to prove that she is funny. She played with her consciousness without knowing what she is getting into. That is literal because she actually left her body and entered his in her attempt to enslave him. She didn't know what she was getting into at all.

The consciousness of a transcendent is their most important asset apart from Origin energy. They can lose their body but they will regenerate it as long as they are still alive. Their consciousness is contained within every part of their body so a transcendent will survive their head getting crushed. The consciousness can be likened to the identity of a transcendent. It is what keeps their body and soul together.