Shakespeare shows his dramatic skill freely in Romeo and Juliet, providing intense moments of shift between comedy and tragedy. Before Mercutio's death in Act three, the play is largely a comedy. After his accidental demise, the play suddenly becomes very serious and takes on more of a tragic tone. Still, the fact that Romeo is banished, rather than executed, offers a hope that things will work out. When Friar Lawrence offers Juliet a plan to reunite her with Romeo the audience still has a reason to believe that all will end well. They are in a "breathless state of suspense" by the opening of the last scene in the tomb: If Romeo is delayed long enough for the Friar to arrive, he and Juliet may yet be saved. This only makes it all the more tragic when everything falls apart in the end.
Shakespeare also uses subplots to offer a clearer view of the actions of the main characters, and provide an axis around which the main plot turns. For example, when the play begins, Romeo is in love with Rosaline, who has refused all of his advances. Romeo's infatuation with her stands in obvious contrast to his later love for Juliet. This provides a comparison through which the audience can see the seriousness of Romeo and Juliet's love and marriage. Paris' love for Juliet also sets up a contrast between Juliet's feelings for him and her feelings for Romeo. The formal language she uses around Paris, as well as the way she talks about him to her Nurse, show that her feelings clearly lie with Romeo. Beyond this, the sub-plot of the Montague-Capulet feud overarches the whole play, providing an atmosphere of hate that is the main contributor to the play's tragic end.
Shakespeare uses a large variety of poetic forms throughout the play. He begins with a 14-line prologue in the form of a Shakespearean sonnet, spoken by a Chorus. Most of Romeo and Juliet is, however, written in blank verse, and much of it in strict iambic pentameter, with less rhythmic variation than in most of Shakespeare's later plays. In choosing forms, Shakespeare matches the poetry to the character who uses it. Friar Lawrence, for example, uses sermon and sententiae forms, and the Nurse uses a unique blank verse form that closely matches colloquial speech. Each of these forms is also moulded and matched to the emotion of the scene the character occupies. For example, when Romeo talks about Rosaline earlier in the play, he uses the Petrarchan sonnet form. Petrarchan sonnets were often used by men at the time to exaggerate the beauty of women who were impossible for them to attain, as in Romeo's situation with Rosaline. This sonnet form is also used by Lady Capulet to describe Count Paris to Juliet as a handsome man. When Romeo and Juliet meet, the poetic form changes from the Petrarchan （which was becoming archaic in Shakespeare's day） to a then more contemporary sonnet form, using "pilgrims" and "saints" as metaphors. Finally, when the two meet on the balcony, Romeo attempts to use the sonnet form to pledge his love, but Juliet breaks it by saying "Dost thou love me?" By doing this, she searches for true expression, rather than a poetic exaggeration of their love. Juliet uses monosyllabic words with Romeo, but uses formal language with Paris. Other forms in the play include an epithalamium by Juliet, a rhapsody in Mercutio's Queen Mab speech, and an elegy by Paris. Shakespeare saves his prose style most often for the common people in the play, though at times for other characters, such as Mercutio.