The Chorus is not a person in Verona but a voice speaking straight to the audience, twice: in the Prologue and at the start of Act 2. Both speeches are Shakespearean sonnets (fourteen lines rhymed ABAB CDCD EFEF GG). Then it never speaks again.

"A pair of star-crossed lovers take their life" (Prologue). "Star-crossed" means thwarted by the stars, not destined soulmates, and "take their life" means both that they are born and that they kill themselves. From this line the audience knows the ending and the lovers never do, so every hopeful scene becomes dramatic irony. As Emma Smith puts it, they are "dead ... even before we meet them".
"Now old desire doth in his deathbed lie, / And young affection gapes to be his heir" (Act 2, Chorus). The love for Rosaline is an old man dying, the love for Juliet a hungry heir at the bedside: even the play's happiest news arrives with a death in the room. Samuel Johnson thought this Chorus "conduces nothing to the progress of the play"; this image argues back.

Use the Prologue to widen any extract to the whole play: AQA's November 2020 report notes that most answers moved from the extract to "the prologue and the feud". The Prologue blames "their parents' rage", where the preface to Brooke's poem condemned the lovers, and the Prince's closing sestet answers its sonnet. The 1623 Folio prints no Prologue and nobody knows why, so never claim Shakespeare cut it.

"A pair of star-crossed lovers take their life" (Prologue). "Star-crossed" means thwarted by the stars, not destined soulmates, and "take their life" means both that they are born and that they kill themselves. From this line the audience knows the ending and the lovers never do, so every hopeful scene becomes dramatic irony. As Emma Smith puts it, they are "dead ... even before we meet them".
"Now old desire doth in his deathbed lie, / And young affection gapes to be his heir" (Act 2, Chorus). The love for Rosaline is an old man dying, the love for Juliet a hungry heir at the bedside: even the play's happiest news arrives with a death in the room. Samuel Johnson thought this Chorus "conduces nothing to the progress of the play"; this image argues back.