Margaery Tyrell convinced Tommen to make the Faith an ally of the Crown .
The ploy works and Margaery finds herself arrested and awaiting trial , although the plot backfires spectacularly and Cersei is arrested as well. Jaime Lannister leads the Tyrell army on the Sept of Baelor to secure Margaery 's release , but it is revealed that she has been absolved by convincing Tommen to forge an alliance with the Faith Alliance .
Margaery Tyrell