Demonic spirits and entities have natures and personalities. The personality of a demon is manifested in whoever He possesses and afflicts.
This is why when you have a spirit of immorality your nature is immoral, when it is a spirit of infirmity, you are always sick, etc.
The moment, it is cast out, even the most violent man becomes the meekest. Because violence was a spirit. It was the nature and personality of a spirit that is now gone.
May we get this deliverance in Jesus’s Name.