The idea of revenging himself on Edgar by marrying Isabella is first put into Heathcliff’s head by...

The idea of revenging himself on Edgar by marrying Isabella is first put into Heathcliff’s head by Catherine. In Emily Bronte's novel "Wuthering Heights", Catherine suggests this idea to Heathcliff in a conversation they have. She tells him that if he were to marry Isabella, he could inherit Thrushcross Grange (Edgar's property) if Edgar were to die without a male heir. This idea sparks Heathcliff's plan for revenge against Edgar, who he believes has wronged him by marrying Catherine.