Soulless villains are motivated by one thing only: getting a soul, as it this case, it was said they used to have one, but lost it for various reasons which in either way, they somehow survived in spite of their soul has been removed from their body.
The tiny deity gloated about his triumph as the machine entered battle mode and erupted into its bipedal shape, immediately charging and firing potent lasers at the capital.
There are lots and lots of entities who gorge on Humanity and if they don't have any, will go to great lengths to obtain some.
These are only slightly more common than being Soulless.
So trying to change them can only end in disaster, especially for the person trying to bring the traits of a soul out in a person that has none.
This is not an easy concept to digest, as we must evolve beyond the desire to put our heads in the sand and ignore the shadow aspects of our world.
Even animals can produce an Aura from their souls.