Nayla was the Fish Speaker body guard assigned to Siona Atreides during the events covered in God Emperor of Dune (novel). While posing as Siona's second in command with in the rebel cell, Nayla was actually acting on direct orders of Leto Atreides II. His orders were simple, obey Siona in everything she commands, regardless of the consequences.
Nayla was pivotal in the climatic scene in God Emperor of Dune (novel). She fired the Lasgun that damaged the bridge, caused Leto and Moneo Atreides, to fall to their deaths. Due to the fact that her participation in the plot had resulted in the death of Hwi Noree, Duncan killed her with a Lasgun.