idk idk just. The speed at which Gloucester was ready to believe Edgar was plotting to kill him. The way every argument Edmund makes against it is so reasonable and reassuring but no matter what he says Gloucester still obstinately insists that Edgar must be planning his death.

Edmund makes a hundred reasonable arguments in Edgar’s defense but he knows they’ll all be ignored.

and then the speed at which Edgar believes that Gloucester is furious with him and wants him dead. So furious and so set on killing him that any attempt to approach him personally and sort things out might cost him his own life.