Charles II was easy-going and quite "casual" in many of his moral attributes (perhaps in reaction to the Cromwell period when quite the opposite views prevailed). Though highly intelligent, Charles was lazy and inclined to let matters look after themselves. While his private life was notorious throughout Europe, he was popular with his subjects.
Charles' heir (as his wife was childless) was his brother James, Duke of York--serious, hardworking, narrow-minded, and exceedingly unpopular.
Charles, with his usual careless ways, paid little attention to his personal safety. James chastised him and advised a less public presence for the king. There was, after all, always the chance of assassination.
"Nonsense," replied Charles, patting his brother on the shoulder. "There isn't a person in England who would dream of killing me in order to make you king."