In Shakespeare's Romeo and Juliet, Friar Lawrence and Paris do have an impact on the tragic deaths at the end of the play. First of all, when Friar Lawrence finds out that Juliet is suicidal in act 4, scene 1, and that Lord Capulet is forcing his daughter to marry Paris in a couple of days, he comes up with a plan to fake Juliet's death. This will allow her to avoid marrying Paris and give Friar Lawrence time to send a message to Romeo about their plan. It's the only plan he has to stop Juliet's attempt to kill herself and reunite the lovers in Mantua. If Friar Lawrence had come up with another plan for Juliet, rather than faking her death, the tragic ending may have been avoided. He could have advised her to marry Paris to save everyone's lives, for example. But he chooses to fake her death, which eventually causes more problems than it solves.
Paris, on the other hand, forces a tragic ending on his part when he challenges Romeo to a duel over Juliet's "dead" body. When Romeo enters the tomb, Paris realizes that Romeo is the one who killed Juliet's cousin, Tybalt. Paris then assumes that Romeo is there to do more harm to the dead bodies. When confronted, Romeo gives Paris a chance to leave him alone with Juliet's body by saying, "Good gentle youth, tempt not a desp'rate man./ Fly hence, and leave me" (V.iii.59-60). If Paris had done what Romeo told him to do, he could have saved his own life. Instead, three young people wind up dead in the last scene, rather than two.