Duncan felt his mind tremble as he realized the truth.
The fact that the black heart was guiding him toward his true self came with a lot of other implications as well. And the most important implication was that he was currently straying away from his true self.
This wasn't good at all.
Unlike righteous path cultivators, one of the core tenets of the demonic path was to be true to your self. Righteous path cultivators pursue righteousness and being in harmony with the world.
Even if they weren't righteous or harmonious, their actions tend to be righteous. Even when they commit crimes, they would use a righteous excuse to commit them.
Like the Buddhist monks stating that they are suppressing devils and establishing virtue. Like the saying that there is no gain without paying. There were all kinds of philosophical arguments used by the righteous cultivators while doing something.
And there is an underlying reason for it.
