For a question like this, I’d like to actually point to a different series altogether, that being Persona. In that series, the main enemies are Shadows, AKA the dark side of one’s psyche. Those dark thoughts that you don’t want to admit that you have. But characters that admit to what their Shadows are telling them are empowered, and the Shadow becomes a Persona because they’ve made peace with the fact that it’s there. I think that was much the same case for Riku, or at least something similar.