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Romeo: "The son of Montague, Romeo is first introduced to us as a sad, melancholic, apathetic youth. His reason for sadness is universal; Rosaline his love will not return his affections."
Juliet: "Lord and Lady Capulet's daughter, she meets Romeo at her father's party and falls instantly in love. She secretly marries Romeo, and, when he is exiled, agrees to the desperate plan to fake her death. She is a young girl who grows in strength and maturity throughout the play."
Mercutio; "The prince's relative and Romeo's friend, Mercutio has a tough and bawdy wit, which contrasts with Romeo's passion and romance. He is killed in a fight with Tybalt, resulting in Romeo's losing his temper and killing Tybalt, Juliet's cousin."
Paris: "A young nobleman, Kinsman to the Prince. Introduced to us in Act I, Scene II, it is Capulet's desire that the young Paris marry his daughter Juliet."
Friar Laurence: "A Franciscan priest, he plays a crucial role in the play by marrying Romeo and Juliet's in his cell in the hope that the feud between the Montague's and the Capulet's will now end."
Nurse to Juliet: "In many ways a surrogate mother to Juliet, she cares deeply for Juliet's best interests, even encouraging Juliet's dangerous relationship with Romeo in the hope that it will make Juliet happy."
Not enough space is allotted to the answer section to give you a full analysis of all the characters you've asked about. Fortunately, you don't have to rely on an editor alone. You will find detailed discussions of each of these characters in the eNotes study guide. Click on one of the links below and then click on the Character Analysis link on the righthand side of the page. A drop-down list will appear. Just click on the name of the character for his or her analysis.