You can always spot a hero from the way they behave to those who are beneath them socially, be they animal or human, because heroes are always kind to underdogs of every species. We can spot the hero in, for example, Georgette Heyer novels, because he is invariably good with dogs. Dogs that are frightened of strangers accept his attention, often positively fawning with delight as the hero finds exactly the right spot behind the ear to scratch.
Okay, so it's become a cliche, but compare with a character such as Blanche Ingram in Jane Eyre. She may be beautiful, but we know she's a baddie because she's so unpleasant and condescending to the staff (including, of course, Jane Eyre herself). Mr Rochester can be careless of other's feelings, but makes amends when he realises. (And Pilot the dog loves him so under that brusque exterior he's obviously okay.)
Contemporary heroes may not have servants but there are waitresses and shop assistants to be considerate to. Hannibal Lecter may be a cannibalistic monster who'd eat your liver as soon as look at you, but he is polite to Clarice Starling even as he toys with her emotions and fears. Scarlett O'Hara, for all her many faults, is devoted to her Mammy. As readers we sympathise with underdogs, and we loathe those who are mean or nasty to them. Make sure your main characters never kick the dog.