Certainly Fortinbras acts as a foil to Hamlet with respect to the theme of action and revenge. For, his situation closely resembles Hamlet's: his father has been killed, and his uncle now reigns Norway. A man of action, he wishes to regain the land lost in Norway during the period of uncertainly after King Hamlet's death. However, he is forced to cease hostilities when King Claudius begins negotiations with the uncle of Fortinbras. Nevertheless, Fortinbras remains a man of action as in Act IV as Fortinbras prepares to enter into battle, "a promised march over his [Hamlet's] kingdom," Hamlet observes,
a delicate and tender prince
Whose spirit, with divine ambition puffed,
Makes mouths at the invisible event,
Exposing what is mortal and unsure
To all that fortune, death, and danger dare,
Even for an eggshell. Rightly to be great
Is not to stir wihout great argument,
But greatly to find quarrel in a straw
When honor's at the stake. How stand I then,
That have a father killed, a mother stained,
Excitements of my reason and my blood,
And let all sleep, while to my shame I see
The imminent death of twenty thousand men
That for a fantasy and trick of fame
Go to their graves like beds....
O, from this time forth, my thoughts be bloody, or be nothing worth! (IV,iv,50-68)
Moved by Fortinbras who risks his life for honor, the Prince of Denmark perceives himself in contrast, and assumes the role meant for one of noble nature, acting at last to avenge his father and rid Denmark of its corrupt court.
The better question is, "Who's not a foil of Hamlet?" The answer is "no one."
In other words, everyone's a foil for Hamlet. Specifically, there are three sons who try to avenge their father's deaths: Hamlet, Laertes, and Fortinbras. Together, their actions and words develop the themes of revenge and death.
Here's the breakdown:
- Hamlet wants to kill Claudius for killing his father (personal revenge).
- Fortinbras wants to take revenge on the entire country of Denmark (political revenge) because Hamlet's father, who's already dead, killed his father.
- Laertes wants to kill Hamlet for killing his father (personal revenge).
Here's the state-of-mind breakdown for each character:
- Hamlet waits to get his revenge. He's too slow.
- Laertes wants his revenge right away. He's too quick.
- And Fortinbras at first demands revenge, but then he waits and gets it later. He's just right.