The thing in Heathcliff’s chest had twisted and hardened over the years. Heathcliff did not mourn this fact. It was pure survival that made him what he was. But he did have to wonder if this act of transformation rendered it something other than a heart.
Huge portions of his heart, if the organ could still be called so, were dedicated to Hareton. This was no sign of affection but rather a product of how revenge consumed him.
Hareton, however, did love Heathcliff, with more heart than he could physically possess. This pleased the wickedest parts of Heathcliff very much.