Initially, these three characters seem to have little in common, but they do share some similarities: all three have lost their fathers. Hamlet's father killed Fortinbras's father. Hamlet's uncle killed the former King Hamlet. And Hamlet kills Laertes's father.
They have all suffered great loss, and thus all three seek to right the injustices they have suffered. Hamlet wants to avenge his father's death (at least he gives it great thought for much of the play). Laertes wants Hamlet to pay for the death of Polonius, and he also seeks justice for Hamlet's mistreatment of his sister and Hamlet's former lover, Ophelia. And Fortinbras wants to reclaim the Norwegian territory on behalf of his father's honor. Beyond that, the three are pretty different.
Hamlet is a man of inaction. He can't decide whether the ghost is real or not. He can't decide if he should kill Claudius or not. He breaks his commitments to Ophelia and wallows in self-pity (whether real or feigned to achieve his own purposes) for much...
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