When Mercutio is killed, Romeo, who has just married Juliet, is motivated by revenge. He had refused to fight Tybalt, telling him that he had reasons unknown to Tybalt to "love" him. He is referring to his marriage to Tybalt's cousin Juliet, which means he is now a kinsman of his former enemy. Mercutio interprets this as a "vile submission," and challenges Tybalt to a duel. Tybalt kills Mercutio when Romeo attempts to restrain him, and his death is thus on Romeo's hands. Romeo resolves to avenge his good friend's death. He chides himself for allowing Juliet's love and beauty to make him "effeminate" and says his love has "soften'd valour's steel." When Tybalt returns to the scene, Romeo attacks him and kills him in a brief duel. He realizes that, by doing so, he has at best made matters more complex—he describes himself as "fortune's fool" and says even before killing Tybalt that Mercutio's death "begins the woe others must end."