- Loras' trial in Season 5. It begins with Cersei making the idiotic decision to arm and legitimize the Faith Militant. Then, when menacing armed men come for Loras, immediately after training, he doesn't think to try to get back his sword. Then, at his trial, Olyvar for some reason testifies against Loras, incriminating himself in the process (which is a double-whammy because Loras was an idiot for resuming his relationship with Olyvar after he betrayed him once already). Fortunately, Olyvar's (fictional) testimony had a convenient explanation... the crux of the testimony was that Olyvar knew of a birthmark on Loras. Therefore, they had to be lovers. Except that Olyvar's claim was that he was Loras' squire... someone whose job includes helping Loras get dressed. So if Loras pointed that out, he could be in the clear. Or he could instead yell and lunge at Olyvar instead, cementing his guilt. This also ignores that, even if Olyvar wasn't his squire, men saw each other naked all the time in medieval times.
- General consensus is that the Dornish story arc in Season 5 suffers greatly from this; from Jaime's ill-planned attempt to 'rescue' Myrcella in the first place, to the constantly stupid and petty behavior of the Sand Snakes, to the fact that Myrcella dies anyway via coming into close contact with Ellaria who, while reprieved, had already made an attempt on her life. It somehow gets even dumber in Season 6: Ellaria murders Doran and Trystane, for being "too weak" to avenge Oberyn. Ellaria has killed Oberyn's brother for refusing to go to war with the Lannisters and Trystane for basically no reason, she has now exterminated Oberyn's house, screwed over Dorne's relationship with the Iron Throne, and as she was never Oberyn's wife, she nor any of her daughters have any claim to the rule of Dorne. All for "revenge".
- Much of the conflict in the final two seasons is all completely reliant on the anti-Lannister forces completely disregarding the threat posed by Euron's Iron Fleet. There's absolutely no attempt to destroy the Iron Fleet or even keep tabs on its location, leading to Euron successfully ambushing Daenerys' forces multiple times without difficulty.
- There are so many glaring issues with the tactics in the Battle of Winterfell in Season 8.
- First, the human alliance completely wastes the entire Dothraki army in a senseless frontal charge that was doomed from the start since cavalry charges rely on breaking enemy morale and formation, which aren't a concern for the undead.
- Second, the cavalry charge also nullifies the living's artillery advantage by allowing just one salvo before risking friendly fire.
- Third, they draw up the entire army not only outside the fortress itself but also beyond the defensive trench turning them into obstacles for their own retreat instead of the enemy charge.
- Fourth, they place their artillery in front of their infantry so that it is the first thing overrun.
- Fifth, many lives are unnecessarily lost due to the over-reliance on Dany and Drogon lighting the fire trench when Daenerys flies too far from Winterfell to see the signal, and it doesn't occur to anybody to have a backup fire source. Even more egregious was that Jon was perched on the Godswood with Rhaegal right next to the trench and doesn't realize nor is informed it needs to be lit.
- Sixth, after managing to retreat within the castle and light the trench the defenders just calmly watch until the undead start managing to cross and only then start scrambling their archers and other defenders to the walls.
- Seventh, it doesn't seem to cross anybody's minds that sheltering the noncombatants in a crypt full of corpses when fighting a necromancer like the Night King. Sure enough, the corpses in the crypt come to life and massacre the civilians.
- Eighth, after Daenerys provides Jon with some much needed air support, she lands Drogon on the ground, which allows them to be swarmed by wights and Daenerys is knocked to the ground, directly contributing to Jorah's death when he leaps in to protect her. The Night King counters all of this with his own obvious mistake of exposing himself before the castle is secure just for the personal satisfaction of killing Bran, even though having his wights Zerg Rush Bran, having undead Viserion incinerate him in a single strafing run, or having his White Walkers seize Bran and then wait till the castle was properly subdued would've accomplished the same thing.
- Season 8 relies on alienating Daenerys and deeming her mentally unstable, something which was never an issue in-series before Jon appeared as a candidate for the throne.
- First, despite her personally defending Winterfell during the battle against the White Walkers, Daenerys is shown sitting alone at dinner, with no Northerners even trying to get into the queen's good graces or establishing ties for future relations. Instead, Varys already regards her like a ticking time bomb, despite her not having done anything at this point.
- Later on, as Daenerys is in a depressed state over losing her closest friends and another dragon-child, everyone including her seems convinced that she can only "rule through fear" and gain no love from the smallfolk. However, this ignores Cersei being a notoriously unpopular queen (instead of a tough act to follow) and the very real possibility of simply setting reforms to win the public's favour (e.g. distributing free food, improving sanitation, rebuilding the Sept of Baelor).
Idiot Plot / Game of Thrones