A veteran of the war
As a veteran of the war, Kelvin is experienced with various armaments and is cool under fire. He is however not your average grunt. His analytical skills and intelligence on the battlefield earned him numerous promotions during the war and it was these credentials that got him a job as a detective when the war ended. Being formerly in the Army, he is well used to taking orders from superiors, although his pragmatism coupled with his experience may have him question authority and bend the rules should he find them "incorrect".
Despite such traits, he is a relatively quiet and reserved person. He prefers to keep things to himself unless you're closely acquainted with him. His reserved and coolheaded nature doesn't make him exactly the best interrogator, being seen as too passive with his suspects. Get past his reservations, he is a compassionate and loyal individual.
Outside of work, Kelvin is single and apart from meeting former members of his unit (which are his closest friends) he usually spends them at the city's numerous night clubs usually sitting alone with a glass of liquor.