I speak, of course, of The Crying Game.
Whitaker plays Jody, a British soldier who is kidnapped by the IRA. As have many prisoners before and after him have done, he attempts to gain sympathy from the guy chosen to guard him, played by Stephen Rea. During their conversations about people and their ability to change, he tells of the old fable that concerns a scorpion and a frog:
Jody: "Scorpion wants to cross a river, but he can't swim. Goes to the frog, who can, and asks for a ride. Frog says, 'If I give you a ride on my back, you'll go and sting me.' Scorpion replies, 'It would not be in my interest to sting you since as I'll be on your back we both would drown.' Frog thinks about this logic for a while and accepts the deal. Takes the scorpion on his back. Braves the waters. Halfway over feels a burning spear in his side and realizes the scorpion has stung him after all. And as they both sink beneath the waves the frog cries out, 'Why did you sting me, Mr. Scorpion, for now we both will drown?' Scorpion replies, 'I can't help it, it's in my nature.'"