A Shakepearean tragedy conveys the sense that human beings are doomed by their own errors or natures, or even an ironic twist of their virtues, or through the nature of fate or the human condition to suffer, fail, and die. In Shakespearean tragedy, the hero usually dies as a result of his tragic flaw, moral weakness, or inability to cope with unfavorable circumstances.
One common weakness that many characters share in Shakespeare's Romeo and Juliet is impetuousness. And, as a result of their impulsive personalities, accompanied by the unfortunate circumstances of fate, Mercutio, Romeo, and Juliet all die.
For these tragic deaths in Romeo and Juliet the reader is well prepared. First of all, the Prologue to Act One mentions that fate has a hand in the tragedy--"the star-crossed lovers"--and the enmity between the Capulets and Montagues breaks "to new mutiny." The first scene opens with strife and renewed hatred. When Romeo falls in love with the child of his family's mortal enemy, there is certain foreboding of a tragic end for the lovers. Certain speeches foreshadow the tragic ending as well. For instance, when Friar Laurence cautions Romeo, saying,"These violent delights have violent ends"(II,vi,10), and Juliet declares, "My only love sprung from my only hate" (I,v,133), there is foreshadowing of Romeo and Juliet's doom since they are too quick in their love too swift in their actions, and circumstances work against their marriage.
Then, when Friar Laurence and Juliet plan her feigned death so the parents will be so relieved to have her alive that they will not be too upset with Romeo, whom she has already married, and the message that Juliet lives does not reach Romeo in time, fate's hand enters the play. The tragic delay to Romeo's knowing Juliet is really alive, coupled with his cries of "O, I am fortune's fool!" prepares the reader for the unfortunate results, results that still bring a poignancy to the audience. For, the beauty of such young, romantic lovers is what dreams are made of, not tragedies.