In Star Wars: Episode VI - Return of the Jedi, Darth Vader redeemed himself by defeating Emperor Palpatine, but Leia still saw him as a monster.

When Luke Skywalker confronts Darth Vader on Cloud City in the final battle of The Empire Strikes Back, the dark lord encourages him to embellish his harshest and most chaotic emotions.

The scene in which Vader says the disputed line comes about an hour and 51 minutes into the film. Luke has arrived in Cloud City and is in a lightsaber duel with Vader.