In my opinion, several characters in the play could have prevented the tragedy of Romeo and Juliet. Here are two characters and their potential impact:
1. Friar Laurence - 60%: Friar Laurence played a significant role in the events leading up to the tragic ending. He agreed to perform the secret marriage ceremony for Romeo and Juliet, hoping that it would help end the long-standing feud between the Capulet and Montague families. However, he did not fully consider the consequences of his actions, such as the potential danger in keeping the marriage a secret, and the fact that his plan to reunite the couple relied heavily on chance. If Friar Laurence had thought more carefully about his actions and their consequences, he could have prevented the tragedy.
2. Lord Capulet - 40%: Lord Capulet was Juliet's father and played a key role in the events leading up to the tragedy. He arranged Juliet's marriage to Paris without her consent, which led to her desperation and ultimately to her seeking Friar Laurence's help. Capulet was also quick to anger and threatened to disown Juliet when she refused to marry Paris. If he had been more understanding and patient with Juliet, he might have been able to prevent her death.
Overall, I believe that Friar Laurence could have done the most to prevent the tragedy by being more responsible and thoughtful in his actions. However, both Friar Laurence and Lord Capulet played significant roles in the events leading up to the tragedy.