Aftran 942 (pool-sister)
|Behind the scenes|
Estril 731 was the pool-brother of Aftran 942. While Aftran was assigned the human Karen as her host, Estril remained in a Hork-Bajir host body, assigned to general guard duty for the Yeerks during the invasion of Earth.
While serving as a reinforcement guard for a meeting of The Sharing, Estril was called into battle against the Animorphs, who had chosen to infiltrate the meeting. He fought against Cassie, in her wolf morph, and was killed by her.
Later, Cassie was briefly infested by Aftran, who accessed her memory of killing Estril. As she did, Cassie felt guilty about having killed him. It was this act of killing that had prompted her to leave the Animorphs for a short time.