Desiderium

Desiderium is the name of the substance found within the brains of all creatures of the multiverse. Desiderium can be explain as the substance that translates one's soul into matter, storing the data of one's personality and desires. Desiderium is the reason why menassec relationships work like they do.

Desiderium coming in contact with someone's body can change their body to change to fit better with their personality or desires.

Desiderium Ion
Desiderium is used as a nuclear power source. It's more effective at changing one's body to match their desires, but it's also harmful for the physical health of a being.