Hay was hulkingly large with broad shoulders and black curly hair. He seemed perpetually calm and walked with a casual stroll. He was curious, a good listener, brave, trustworthy, and always ready with a joke or pleasant story. He did not become inebriated easily.
In spring 2273, he was assigned to protect Rear Admiral James T. Kirk in 2273 during a clandestine trip to Neural along with Giancarlo Rowland and his friend, security guard Apryl Burch. The four traveled to Neural together aboard the civilian transport ship Captain Cook.
During a Freeholder celebration after Victory slavers had been routed, he joined the party and appeared to drink the local alcoholic beverage, but would dump out the liquid when others weren't looking, to remain alert.
Hay was killed in Providence Valley during a Victor raid on Freeholders who were harvesting produce. He was shot twice in the chest and once in the neck, part of an attack intended to capture Kirk, who'd been spotted earlier by Klingon surveillance equipment. Widowed Freeholder Elanna took his death particularly hard, and Burch fought back tears. The landing party buried Hay on Neural and Kirk gave a memorial speech. His body was later retrieved by the USS Potemkin to return to Earth. (TOS novel: Serpents in the Garden)