Act 3, Scene 3 opens with this conversation between Gloucester and Edmund:
Alack, alack, Edmund, I like not this unnatural dealing. When I desired their leave that I might pity him, they took from me the use of mine own house; charged me, on pain of their perpetual displeasure, neither to speak of him, entreat for him, nor any way sustain him.
Most savage and unnatural!
What is the source of dramatic irony in this conversation?