Cersei manipulated her cousin with sex in the earlier seasons of Game of Thrones in order for him to do her dirty work.
However, by the time the season five finale rolled around, Lancel had found a new faith, following the High Sparrow (Jonathan Pryce).
The Sparrows had effectively taken over King’s Landing and, despite her royal status, Cersei faced a humiliating punishment for her adultery with Lancel, although she managed to keep the Jaime romance under wraps.
Cersei was stripped naked and in memorable scenes, paraded through the streets of the capital to hoards of furious residents.