So I have decided to write in third person and the book will almost exclusively be from one characters perspective, with the occasional head jump that is only a few lines long, and rarely I might add. Furthermore, the book will have a omnipotent narrator, for instance, the narrator will tell how the character feels: “Fendraels father rushes over to him and lifts him up on his shoulder, the people in the crowed are cheering. Infected by the energy in the air, Fendrael starts cheering as well, he has never felt so accepted and it feels like he could do anything.” but I avoid narrating information about the world, for instance I will have character interaction to convey such information: Fendrael walks through the hallway until he reaches the living room, his father is sitting with an old friend in the right corner of the room, discussing. “We live in bad times Perael, I have heard that 10 more cities in the central region has seceded from the authority of the emperor, this does not bode well for us, sooner or later we will be affected by the uprising as well”, says Garret, a friend of his father. “Nonsense Garret, we are in the southern region of the Empire, far away from the turmoil, and don't forget, our duke is a close friend of the Emperor, the security here is beyond the capabilities of a mere rebel army”, Fendraels father says. But that is difficult sometimes, so I was wondering, is it possible to tell something that the character knows but something that he is not explicitly saying or thinking?
Like this for instance: "The colosseum is shaped as a perfect circle and the seats are 20 meters above the ground. Fendrael has read that there has been occasions when there has been really huge monsters at display, but that was several hundred years ago. With the exception of a few dense forests and high mountain areas, monsters are rare on the main land in the Empire nowadays. Suddenly the Duke stands up and raises his hands to signal the audience to be quite. Everyone wants to know about the special event so the noises dies down quickly".
Okay, first of all, it's not an "omnipotent" (all powerful) narrator, it's "omniscient" (all knowing). Of course the narrator will know what the POV character is feeling. An omniscient narrator knows what all the characters are thinking. Celeste Ng uses an omniscient narrator in All the Things I Never Told You. When narrating, there are two pitfalls you have to be careful to avoid - filtering and an over-reliance on telling as opposed to showing. Filtering is stating that someone is seeing or hearing something rather than just describing what he is seeing or hearing: "He heard a shot ring out." Better would be "A shot rang out." The same information is conveyed, but the former is reporting what the character experienced while the latter allows the reader to experience it, too. Telling (and there are lots of discussions on this site) is a simple summing up rather than describing. "She was shocked at the news." Showing describes what the character experiences: "The room lurched; she had to hold on to the chair to steady herself. Breathing was difficult as she sat down to absorb the news."
It's best to weave this sort of thing in carefully. When characters tell each other things that they both know, they're obviously doing so for the sake of the reader. You'd be better off either (1) finding a more subtle way for the characters to communicate it, including mixing it up with other elements or (2) just having the narrator communicate it. (2) is fine when the characters don't know the information--often a simple quick explanation keeps the story rolling better than a bunch of dialogue that exists for no reason other than communicating that information. But sometimes you can find another reason. An example of how I might communicate your example. I stick to the present tense, but otherwise it's kinda sorta in my voice: Fendrael wanders into the living room, yawning and hoping for breakfast. He grimaces in disappointment to see old Mr. Garrett lounging on the bench chatting with his father. When those two get started, they could argue well past lunch. Garrett says, "It's not a little rebellion here and a little rebellion here any more, it's ten cities. Probably more tomorrow. No, that's not much land, but what good is an empire of potato fields and nothing else? The Emperor will fight for those cities. The war is coming." Potatoes. Mmmm. Fendrael sighs and sits down by the kitchen. He stares fixedly at his father. Breakfast. Breakfast. Breakfast. Fendrael's father snorts. "No. Those cities rotted from the inside; the rebels just finished the job. The Duke is loyal and so are his people--and an army would have to cross half a continent of those worthless potato fields." Breakfast? "Potato fields make good food for a traveling army." "Oh, for--" Fendrael's father finally notices Fendrael. "Here, boy, go peel us some potatoes and start them frying. We have a guest." Fendrael's eyes widen in horror. Cook? Him? "But I'm not hungry!"
