In A Feast of Crows, Cersei is beginning to figure out that her new daughter-in-law is going to be hard to control. Already she has managed to drive a wedge between Tommen and Cersei. Cersei is determined to prove that Margery has been unfaithful to Tommen and thus have the marriage anulled. One of those plans involves having one of the more handsome knights, a Kettleback boy, to seduce Margery, then give testimony against her.
