Just....didn't make much sense the way it was presented. Any other point in the series Cersei has 10-15 goons with her for no reason....well, the reason being she's the "queen"....but she goes and meets with a religious cult in the slums of King's Landing with literally not one guard? shyt was
as hell. Then the fall out with Tommen not lifting a finger to help her....I realize he's a bytch and I'm not a book reader so the whole thing was probably done a lot better and more subtly in the books....but I thought the whole thing was written terribly on the show.
Fred.
Aight, I feel you. Yeah, sloppy.
In the books, it's a highly compelling three-way, high-stakes, high speed chess game.
Cersei, upset with the rising influence Marg (and thus Olenna) is having on Tommen (including Tommen admiring Loras and wanting him to teach him combat), hatches a plot. Peeping the rising influence of the Faith Militant (they’re presented less as an extremist cult, more of like, die-hard born agains, bordering on extremism with their devotion, more like a conservative, Islamist right-wing political party), Cersei decides the only way she can get rid of Marg safely is through the Faith Militant. Unfortunately for her, she overthinks her stand with the Faith and never considers that they’d treat her the same, or that Olenna would cease the opportunity to press her the same way she presses Marg.
It’s another case of Cersei catching an L because of a massive oversight she makes through overconfidence, which is a constant with her in the books. Cersei is the books is always a victim of hubris. The reason Tommen never does anything about her (or Marg) being taken is Cersei talks him into (or does it herself, can’t remember) granting the Faith Militant unchecked authority in matters of faith.
And also, something that isn’t stressed in the shows to really drive home the situation, is that the Faith Militant are incredibly popular in Kings Landing. They’re a populist movement at a time when the kingdoms are being destroyed by the whims of nobility, and Cersei (and Marg) being held is supported by the people. Not only did Cersei tell Tommen (who btw is like 8-9 years old in this storyline) to give the Faith this authority, the nobility storming in and taking them out would cause a riot and the city would burn.
The people of King’s Landing would probably revolt and everyone there would die. It’s a zero-sum game. Basically, Cersei played herself, throwing the same dirt at an enemy that she’s covered in, thinking the ambitious and righteous would fall in line with her because she’s the one who gave them that power.
Sidenote, Book Cersei is not as smart Show Cersei. That makes a lot of things that befall Show and Book Cersei feel out of place because of how god-tier Show Cersei is with the calls. Book Cersei is a cunning opportunist, but wildly over-confident, spiteful, and short-sighted. Tyrion, Tywin, and Kevan Lannister clean up all of her messes. They levelled her up big time in the show, and as a result it’s hurt some stories, and some characters (Jamie).