During act 3, scene 3 of The Tempest, Alonso, Antonio, and Sebastian are attended upon by a series of spirits who serve them a banquet while Prospero looks on undetected (this is a spectacle being staged in order to terrify the men in service of Prospero's revenge). However, the food quickly disappears and their comfort is replaced with sheer terror. Before the trio can eat a bite, Ariel appears in the guise of a harpy and delivers a fearsome monologue that seems to threaten the three men with imminent destruction:
You are three men of sin, whom Destiny,
That hath to instrument this lower world
And what is in't, the never-surfeited sea
Hath caused to belch up you; and on this island
Where man doth not inhabit; you 'mongst men
Being most unfit to live. I have made you mad;
And even with such-like valour men hang and drown
Their proper selves.
Ariel is saying these men are "unfit to live" because of their past misdeeds, chiefly exiling Prospero and Miranda, not to mention leaving them for dead in the middle of the sea. Ariel aligns himself with fate, his dreadful appearance and harsh words turning him into a living embodiment of Prospero's rage and desire for justice. The claims that the trio are unfit to live also adds to the suspense of the scene. Throughout the play, the audience is unsure just how willing Prospero is willing to go to exact his vengeance upon those who wronged him. The audience (and indeed, the men in the scene) might wonder if those desires will lead to violence.