He was sitting upright in an armchair far too big for his teenage stature, giving the impression of himthat he was sitting on a majestic throne. He was sitting upright in an armchair far too big for his teenage stature, giving the impression that he was sitting on a majestic throne.

or "that he was sat upon a majestic throne" I can't really explain why but using "impression of" here sounds off

He was sitting upright in an armchair far too big for his teenage stature, [giving the impression of him sitting] on a majestic throne. He was sitting upright in an armchair far too big for his teenage stature, [giving the impression of him sitting] on a majestic throne.

The wording here is a little awkward. I think it would flow better to write, "which gave the impression that he was"

In front of him, to his left, was a large, comfortable couch – surely to give audience to distinguished subjects, orand why not his little sister.? In front of him, to his left, was a large, comfortable couch – surely to give audience to distinguished subjects, and why not his little sister?

Needs to be posed as a question "And" because it's in addition to, not one or the other, and can imply the sister is on the same level as a distinguished subject If you want to imply it's one or the other, there are better wordings, such as: "...distinguished subjects, or perhaps just his little sister."

To his right, a roaring fire crackled in the wood stove, warming his tiny royal feet dressed in fancy socks. To his right, a roaring fire crackled in the wood stove, warming his royal feet dressed in fancy socks.

I agree with the other reviewer's comment here. "Tiny" doesn't seem to work here for a teenager. I would just leave it out.

To his right, a roaring fire crackled in the wood stove, warming his tiny royal feet dressed in fancy socks. To his right, a roaring fire crackled in the wood stove, warming his tiny royal feet dressed in fancy socks.

At the least I agree "tiny" is an extreme word here. When you say "tiny feet" people are probably going to think of a baby's feet or something xD

To his right, a roaring fire crackled in the wood stove, warming his tiny royal feet dressed in fancy socks. To his right, a roaring fire crackled in the wood stove, warming his tiny royal feet dressed in fancy socks.

The detail that stands out as possibly being out of place are his tiny feet. It's hard for me to imagine a teenager with feet that small, not that it couldn't be the case, but "teenage stature" suggests that his height is average or normal for his age, so that makes it strange that his feet would not be. (But maybe his tiny feet will be explained later in the story.)

Gathered around athe living room table with a generous choice of drinks and cakes, his parents, grandparents, aunts, uncles, and his cousins were engaged in the animated family conversations of a Sunday afternoon. Gathered around the living room table with a generous choice of drinks and cakes, his parents, grandparents, aunts, uncles, and his cousins were engaged in the animated family conversations of a Sunday afternoon.

Using "a" makes it sounds like there are multiple tables in the living room and they are just using one of them, which is fine if that's what you intended, but it's kind of typical for there to be only one table. Without the specifier of "a Sunday afternoon" not using an article would be fine ie. "...and his cousins were engaged in animated family conversation."

The words gave way to anxious glances, some searching for answers, others trying to avoid an awkward moment. The words gave way to anxious glances, some searching for answers, others trying to avoid an awkward moment.

"His words" might be better, the previous sentence about heavy silence feels like it puts distance between the one in which the father spoke, so re-establishing them as "his words" feels more clear

After a few tense seconds, the discussions resumed hastily and hesitantly, asin a collective effort to erase that disturbing memory. After a few tense seconds, the discussions resumed hastily and hesitantly, in a collective effort to erase that disturbing memory.

"as a collective effort" sounds correct sometimes, I can't really explain why it sounds wrong at other times, like this one. I think "in" suits situations that are currently ongoing and that the subjects are perceiving or involved in, while "as" feels distanced from the situation. Possibly related: if you remove "collective," "as an effort + the infinitive" just sounds wrong

Fortunately, the little king on his throne didn’t notice the brief impertinence of his progenitor. Fortunately, the little king on his throne didn’t notice the brief impertinence of his progenitor.

"Impertinence of his progenitor" sounds funny (in a good way lol), I need to use this to describe my dad's trivial wrongs

[Unfortunately,] his reign was far from over! [Unfortunately,] his reign was far from over!

Since there is no interaction between the nephew and the others, I don't know why it his continuing reign would be unfortunate. The only hints are his self-satisfied smirk and his kind eyes that are not completely innocent, but I'm not sure those attributes are negative enough to support "unfortunately."