Given the abilities of the True Grandmist Body and Devil Emperor's Tome of Eternal Darkness, it wasn't strange for Leon to gain great control over Darkness Energy and not be corroded by it.
However, he wasn't born with this ability.
As such, he couldn't be called a demon in the truest sense, but others could still mistake him for one without prior knowledge of his circumstances.
Nevertheless, there was a proper term for cultivators who willingly embrace the power of the darkness; they are called demonic cultivators.
In the Divine Realm, demonic cultivators were hunted down like any other demons.
It just shows how the deep-rooted fear, hatred, and discrimination the denizens of the Divine Realm have against the creatures of darkness.
'The mastermind who drove my father and me to our deaths are all Peak-stage Divine Kings that stand at the top of the Divine Realm and rule over it.'
Leon recalled.