Alice smiled, "Remember when you gave me your soul, what would you do if I gave you mine?" She muttered lifting her head so she could see Jet's green eyes. She knew that one soul could provide so much energy, how much could her provide him with? She hated this life. She didn't want to be human, or an angel. She didn't mind being a demon if something happened. "As soon as you abandon your emotions then you will become a true demon. With true demonic powers." Lucifer's word rang in her head.
A demon feeds of the sorrow and pain of a soul, the heart-ache, the sorrow. If Alice didn't have one she wouldn't be food for some other demon. But without a soul... wouldn't that make her a zombie?