He is very nervous and easily intimidated by others, stuttering in his speech and going along with plans without fully knowing or understanding what is involved. He only went along with the ritual because he had formed The Blood Pact with Reese, who used that to threaten Kayle. The other cultists do not respect him, insulting him right in front of him and even considering using him as a sacrifice. Despite his devotion to Zamorak, he does not wish to harm anybody.
Kayle is the first cultist you must fight, and uses ranged to attack the player and Xenia, who is hit for 1 damage and her health bar is emptied, though she claims she is more gravely wounded than she is in order to test the player. In combat, he attacks with ranged, and when he reaches full adrenaline, he will use the Deadshot ability.
When he is defeated, he can be interrogated, and then he can be either spared or killed by the player. He drops Kayle's chargebow regardless of the player's choice.
Kayle never moves out of his square. If a player is near death and out of food, they can simply stand into his square and rest instead of running back to Xenia. If you run back, he would hit twice, possibly killing the player. The player can even use the LumbridgeHome Teleport to escape without being interrupted.
He appeared during Reese's memorial during the Festival of the Dead. If he was killed, the memorial was also dedicated to him, but if he was spared, he was a mourner. During the memorial, he stated that he regretted signing up with Reese.