Bill strikes the look of a disheveled journalist type carrying out a pad and paper and studying his environment before he's off on his "journey", wishing those kind enough to treat him hospitality a kind farewell. Bill is not afraid to share some details about his past when asked, such as him growing up in South Africa during his teens, or studying abroad in Canada before becoming licensed to practice what he calls "ethical investigations" which led him to Ukraine less than a few years ago, and eventually Chernarus right before the initial outbreak.
Bill will not mince words about staying in any one place for too long, he's nomadic in nature and is very protective of his goals that he must eventually return to if you've shared an adventure with him. He doesn't take companions for terribly long, but given the right circumstances, he will have your back when you cross paths. Does not take well to conflict.