How do the characters of Romeo and Juliet develop throughout the play?
Juliet begins the play as a beloved daughter, still under the protective wing of her nurse, doing nothing without her nurse's knowledge if not her mother's. When her mother presents the idea of Paris as her future husband, Juliet agrees to consider him. She says, "no more deep will I endart mine eye / Than your consent gives strength to make it fly" (1.4.104-105). In other words, she will not permit herself to feel more than what her parents deem proper. By the end of the play, however, she is more than willing to completely disobey them; she refuses the engagement to Paris procured by her father, even though he essentially disowns her as a result. Further, and perhaps more significantly, she hides her plans even from her beloved Nurse when she drinks the potion that makes her seem dead. Juliet develops total independence from her parents and the Nurse by the play's end.
Romeo develops some independence and maturity when he becomes galvanized by his love for Juliet. Initially, he is really mopey and kind of whiny about Rosaline and her vow of chastity, but once he meets Juliet, he is all action. First, he climbs over her garden walls and then he arranges for a marriage ceremony with the friar. He is coolheaded when Tybalt insults him in the street and, even when goaded by his best friend, he perseveres in demonstrating his newfound maturity. Then, when he does not receive the news about Juliet and the friar's plan, he storms her grave, prepared to end his life to be with her. Sadly, inaction would have served them both better, but his love for Juliet pushes him to act when his feelings for Rosaline never did.
Both Romeo and Juliet mature during the play. In Act I, scene i, Romeo is in love with Rosaline without hope, for she has sworn to remain chaste and single. He is moody and depressed, and in the next scene, when Benvolio suggests he attend the Capulets' ball in order to find a new love, he only agrees so that he will have the opportunity of gazing on Rosaline. As soon as he sees Juliet, however, he forgets his infatuation with Rosaline as he truly falls in love.
Romeo's love for Juliet helps him see beyond the brawl between his family and the Capulets so that in III.i, he tries to stop the fight between Tybalt and Mercutio and even steps between them. He only fights Tybalt after Mercutio has been killed and he feels he must revenge his friend's death. Again, in Act V, he immediately makes plans when he hears of Juliet's supposed death, and when he kills Paris in his attempt to get to Juliet, he honors Paris's wish of being laid next to Juliet in death.
In the beginning of the play Juliet is the model young and innocent daughter. When asked if she would like to be married, she replies, "It is an honor that I dream not of." But after she marries Romeo, Juliet matures beyond her fourteen years and assumes the responsibilities of a wife. She gives up her dependency on her nurse and risks pain and death to remain true to Romeo.