He was very aggressive and had to be held down during experimentation. He had his memory wiped due to large amounts of Element 115 used on him.

Ultimis Dempsey's choice of uniform is his standard-issued green uniform of the United States Marine Corps. It consists of a green jacket and either a black or green shirt with green pants.

Dempsey was selected for this mission after he showed his true grit at the battle for Peleliu. Remarkable though it may seem, his unit was captured.