Willmore is a cavalier, which means that he is a royalist who is loyal to Charles II during the English Civil War. Willmore is a rover, which means that he travels from place to place on board a ship. During the action of the play, he takes a few days in Naples to enjoy Carnival and then plans to again board the ship to lead his itinerant life.
When he arrives in Naples, he says, "love and mirth are my business." He is constantly in pursuit of pleasure and amusement, and when he meets Hellena, who tells him that she is soon to go to a nunnery, he feels equal to the challenge of wooing her. He says, "A Nun! Oh how I love thee for't! There's no Sinner like a young Saint." He promises to be dedicated to Hellena, but he regrets that she has made such an impression on him. He says:
"She has play'd with my Heart so, that 'twill never lie 'still till I have met with some kind Wench, that will play the Game out with me."
In other words, he can't bear to dedicate himself to one woman, and he soon pursues a famous courtesan named Angellica Bianca. He sees her picture on the wall and pulls it down, and then he enters into a fight with some Spaniards. He is rash and impetuous and eager to fight anyone who challenges him.
Throughout the play, Willmore shows little constancy to one woman. As soon as he has pledged his dedicated to Angellica, he finds Hellena during Carnival and begins to flirt with her. He is a rake until the end of the play, when he promises to marry Hellena, who he senses is his equal in wit and cleverness.