Final answer:
Mercutio blames both Romeo and Tybalt for his stabbing, uttering the famous line 'A plague o' both your houses!' as he curses the feud between the Montagues and Capulets that led to his death.
Step-by-step explanation:
In William Shakespeare's play Romeo and Juliet, Mercutio blames both Romeo and Tybalt for his fatal wound. During a confrontation, Tybalt stabs Mercutio under Romeo's arm. Mercutio, in a moment of bitter irony, curses both the houses of Montague and Capulet, saying, 'A plague o' both your houses! They have made worms' meat of me.'
Romeo, who was trying to prevent the fight, feels responsible for Mercutio's injury since it occurred as he intervened. Mercutio's biting commentary on the senselessness of their feud highlights the tragic consequences of the families' animosity and foreshadows the devastating ending of the play.