Short on combat experience, Billy often found himself suffering with shock at the sight of fellow troopers dying around him. This, compiled with his frequent cracking under stress of combat, made him highly ineffective as a soldier. Outside of combat, Billy was as cheerful and bright as any other trooper in the infantry. While in the infantry, Private Lei Sahara often looked after him as Sergeant Rake may rather have killed him instead. While volunteering for a minor errand, he was given a knife by Captain Dax. Later on, Otter, along with Private Brick, were trapped in the barracks of Hotel Delta 1-8-5 by Corporal Griff and Sergeant Peck, and became infected with Control Bugs. After waking up under the Control Bug's influence, Billy went to General Shepherd's office, where he sneaked up on Lieutenant Dill, and used the Dax's knife to kill him. Billy tried to kill Private Sahara, but she shot him to death.