This was especially to be remarked if any one attempted to impose upon, or domineer over, his favourite: he was painfully jealous lest a word should be spoken amiss to him; seeming to have got into his head the notion that, because he liked Heathcliff, all hated, and longed to do him an ill-turn. 
This happened especially if any one attempted to impose upon his favourite: he seemed to think that, because he liked Heathcliff, we all hated him. 