Princess Myrcella Baratheon and Prince Trystane Martell had stayed in the Red Keep despite Queen Margaery Tyrell's insistence that they attend the trial as "followers of the Faith". Myrcella had replied to Margaery's statement by saying "The High Sparrow has no right to force anyone to attend the trial. In addition, any trial would be a sham as the High Sparrow has banned trial by combat via my brother, who is his puppet."
Margaery had replied that "You're attendance will show that you respect the Gods and the High Sparrow."
Trystane said to Margaery, reminding her of his Dornish roots "In Dorne, the Faith has little sway over politics. I do not trust religious fanatics or religious leaders."
Margaery's reply was terse "You are no longer in Dorne and you and your wife would be dead if you were in Dorne."
Myrcella said, not knowing that her refusal to attend the trial of her mother and her brother-in-law would save her life "Still, I have the right not to attend what is obviously a sham."
Margaery had walked out after that.
Myrcella had calmly waited for news on the trial of Loras Tyrell and her mother, Queen Cersei Lannister afterwards but she saw the Sept explode, killing the High Sparrow, Margaery Tyrell, and everyone else in the Great Sept of Baelor
After the explosion in the Great Sept of Baelor, Myrcella and Trystane had walked to the room where King Tommen Baratheon was in as Myrcella knew that Tommen had lost his wife in the explosion as she saw the explosion and Myrcella was there to comfort her brother.
Myrcella told Tommen "You still have me and Trystane even though your wife is dead now."
Tommen replied to Myrcella's statement "My wife is dead and I am a failure as a King. I want to join my wife in the next world."
Myrcella replied, practically begging him not to kill himself "Killing yourself won't change anything, it only will confirm the totality of your failure."
Tommen then said "I will die as Tommen Baratheon, not as King Tommen I "the Useless", I hope that you'll be a better Queen than I was. You are smart and possess our grandfather's intellect without his lack of compassion." He then removes his crown and places it on the table before jumping to his death with tears appearing in Myrcella's eyes afterwards.
Trystane Martell then said "You are now Queen, may the Seven protect us all."
Myrcella didn't say a word afterwards and placed the crown on her head with a lot of discomfort due to what happened to her brothers
Myrcella's coronation was a relatively simple affair as the Small Council was virtually wiped out in the explosion with the exception of Qyburn, who she knew was a sycophant for her mother. She looked grim as she walked to the Iron Throne to formally be proclaimed "Queen Myrcella of House Baratheon, First of Her Name, Queen of the Andals and the First Men, Lady of the Seven Kingdoms, and Protector of the Realm". Unlike her mother, she didn't live in a bubble where her enemies would fall and bend the knee to the new Queen as she knew that her mother's actions had made enemies. She told her husband and her father "The war is lost, the only questions are if we are put to death or our lives are spared by the victors, who defeats us, and when will we be defeated" in the knowledge that House Lannister's authority had disappeared outside of Kings' Landing, the Crownlands, most of the Westerlands, and the Stormlands.
After the coronation, she decided to call a meeting of the Small Council (or it's remnants), which consisted of herself, her mother, who was appointed Hand of the Queen, Qyburn, the Master of Whisperers, and three new appointments to the Small Council, Trystane Martell, her husband, who was now Master of Laws and Coin, which, considering the horrible state of Lannister control over Westeros, meant that he was now in charge of all that's left of civil administration, she also appointed her real father, Jaime Lannister to Master of War and Lord Commander of the Queensguard, and finally, Timos Waller, a minor lord of a coastal keep in the Westerlands known for his competence and his loyalty, was appointed Master of Ships as well.
Queen Myrcella calmly opened the meeting with a statement "How bad is the situation right now?"
Jaime Lannister replied "I have received reports that the Riverlands has fallen into anarchy as Walder Frey has been assassinated and a North-Vale alliance army is marching to reclaim it in the name of the rebel Jon Snow. In addition, the Reach and Dorne have declared for Queen Daenarys Targaryen after the incident in the Sept."
Cersei said "We can still win as the forces of the Westerlands are some of the best in the Seven Kingdoms."
Qyburn said "I concur with the Hand of the Queen and we have an opportunity for victory if a Frey loyalist takes control of the Riverlands."
Myrcella argued back "The situation is hopeless, we have no chance of victory at all, all we can do is to ensure that our defeat is as bloody as possible."
Timos Waller said "What about the Iron Islands? As Master of Ships, I recommend that self-proclaimed "King" Euron Greyjoy be dealt with somehow before he attacks us."
Queen Myrcella then replied "What about Daenarys Targaryen's fleet? It's far larger than Euron's fleet."
Timos Waller then said "Well, Euron Greyjoy is, if Qyburn's little agents are to be believed, building a massive fleet to attack the enemies of the Iron Islands."
Queen Myrcella calmly remarked "Very well, I give your approval to your plan to attack Euron Greyjoy's fleet. The meeting of the Small Council is dismissed."
As the meeting of the Small Council wrapped up, Myrcella told Trystane and Jamie "We have no chance of winning the war, it is best that we surrender and beg for our lives, but if that is not possible, we should make our final battle as bloody as possible. House Lannister has no chance of sitting on the Iron Throne once this is over" before Myrcella and Trystane returned to their quarters.
A/N Timos Waller was an OC minor lord created to represent the total destruction of the major lords by Cersei's actions and the fact that many minor lords are probably seeking this as an opportunity to increase their power
