| Quote #7
When Romeo hears from Balthasar that Juliet is dead (she's not but everyone thinks she is because she drank Friar Laurence's sleepy-time concoction), he declares "I defy you, stars!" Is he suggesting that Juliet's death was fated to happen? If so, how is he going to "defy" the stars, exactly?
Romeo rejects the stars that have decided to separate Juliet and him. He will be with Juliet despite their plans.
| Quote #8
Friar Laurence blames "unhappy fortune" for preventing Romeo from receiving a letter explaining that Juliet isn't really dead.
| Quote #9
ROMEO (to Juliet in the tomb)
Misguided Romeo is convinced that he will defy the "stars" by committing suicide. The idea is that fate is responsible for separating the lovers but Romeo is going to one-up the stars by killing himself, which he believes will reunite him with Juliet.
If you're looking for textual evidence that Romeo brings about his own "fate" (by making a decision (of his own free will) to kill himself, then this is the passage for you.