In Shakespeare’s Romeo and Juliet, Mercutio says, “A plague o’ both your houses!”
Mercutio speaks the line after Tybalt fatally wounds him during a street fight. Romeo has tried to stop the confrontation, but Tybalt attacks Mercutio under Romeo’s arm, and Mercutio is mortally injured. His repeated curse condemns both the Montague and Capulet families for allowing their feud to continue.
The line is important because Mercutio is not a member of either rival household. As Romeo’s friend and a relative of Prince Escalus, he stands somewhat outside the family conflict, yet he becomes one of its victims. His death also marks a major change in the play: Romeo abandons his attempt at peace, kills Tybalt, and is banished from Verona.
A common mix-up is attributing the line to Romeo, who is present during the scene. Romeo instead says that the feud has made him “fortune’s fool” after Tybalt’s death.