There is a linguistic divide between the aristocrats and commoners in terms of blank verse and prose, but the division is not black and white. The servants, including Gregory, Sampson, Peter, and Abraham, speak in prose. Gregory and Sampson follow the regal prologue, which is in verse, with a crude conversation in prose.
The prologue begins:
Two households, both alike in dignity,
In fair Verona, where we lay our scene,
From ancient grudge break to new mutiny,
Where civil blood makes civil hands unclean.
Sampson taunts the Montagues in prose: “Nay, as they dare. I will bite my thumb at them; which is a disgrace to them, if they bear it. . . . No, sir, I do not bite my thumb at you, sir, but I bite my thumb, sir.”
The aristocratic Tybalt and Benvolio interrupt the quarrel between several commoners with verse, as do the heads of the Montagues and Capulets.
The romantic poetry, as spoken by both Romeo and Juliet, and formal scenes, such as those between Paris and Lord Capulet, are in verse. The Nurse, who is definitely a commoner, speaks many of her speeches in verse, in spite of their often inappropriate subject matter. It is more predictable that Friar Laurence talks in verse.
Romeo uses prose several times, first when he reads a letter about the Capulet party and later when Benvolio and Mercutio mock him and taunt the nurse. During this scene, both Benvolio and Mercutio, who usually speak in verse, also talk in prose. The poor nurse speaks in prose when the young men hassle her, but Romeo reverts back to verse when discussing Juliet—and then the nurse rambles on in prose.
Benvolio, Tybalt, Lord & Lady Capulet, Prince, Lord & Lady Montague, Romeo, Paris, Mercutio, Juliet, Chorus, Friar Lawrence.
Gregory, Sampson, Abraham, Officer, Servant, Nurse, Peter.
Some characters speak both in prose and verse (Romeo, Juliet, Mercutio, Benvolio)