So like the title says I'm having trouble writing this character. He is truly omniscient (he can see everywhere and read people's minds and has been doing this since the very beginning of the book's setting), but for almost the entirety of the story he is unable to truly interact with the world barring little things here and there until near the end when the main character finally confronts him. The story itself is basically this omniscient character's tale of how the main character defeated him.

The problem is that I'm not sure how to write this character as his own person without disrupting the flow of the story. I've thought of writing him in a similar way to how Hunter S. Thompson wrote his character Raoul Duke where while telling the story Duke often goes on tangents about himself or his thoughts on the situations he or people around him are experiencing, but unlike Duke my character isn't the protaganist of the story and I'm not sure its a good idea to introduce the narrator before the protaganist when they are two different people (not to mention that the narrator's identity is supposed to be a surprise revealed at the end). Also I'm not entirely confident that a Thompson-esque narration would work in what is supposed to be a science fantasy story.

So what do you guys think? Any ideas?