After the Dark Mark appears in the sky on the night of the Quidditch World Cup, Barty Crouch releases Winky the house-elf from his service, and her unfair treatment draws Hermione’s sympathy and indignation. When she, Harry, and Ron visit Sirius in the cave above Hogsmeade to discuss concerning current events, she describes Crouch’s treatment of Winky, and Ron snaps at her to let it go. In Hermione’s defense, Sirius tells Ron that she understands Crouch’s character better than he does, then offers, “If you want to know what a man’s like, take a look at how he treats his inferiors, not his equals” (GF27).
This quote is particularly interesting coming from Sirius, whose ultimate downfall is his treatment of Kreacher, his family’s house-elf. When Harry and Dumbledore speak after Sirius’ death in the Department of Mysteries, Dumbledore tells Harry, “[Kreacher] was forced to do Sirius’s bidding, because Sirius was the last of the family to which he was enslaved, but he felt no true loyalty to him. And whatever Kreacher’s faults, it must be admitted that Sirius did nothing to make Kreacher’s lot easier–(OP37).” When Harry protests, Dumbledore continues, “Sirius was not a cruel man, he was kind to house-elves in general. He had no love for Kreacher, because Kreacher was a living reminder of the home Sirius had hated” (OP37).
More than anything, the schism between Sirius’ thoughts and behaviors towards house-elves reveals that intentions do not always equate to actions, and a troubled past complicates this. We are the sum of our choices, and that includes the involuntary, reflexive choices we make that do not always comply with our belief systems. Sirius believes that Barty Crouch is a bad man because of his behavior toward Winky, and perhaps he understands that his behavior toward Kreacher is similarly reprehensible. Sirius dislikes Kreacher because he is a living reminder of the views his family espoused, which he does everything in his power to reject, repurposing Number Twelve Grimmauld Place as Headquarters for the Order of the Phoenix, while reflecting bitterly that this has been his primary contribution to the Order. Sirius’ upbringing in a traditional, blood status-obsessed Pureblood home must have shown him the ugliness of treating underprivileged people disrespectfully. While he chose to rise above that particular family trait, he clearly struggles with it when it collides with reminders of that past, i.e. Kreacher.
To a degree, Sirius’ adolescent bullying of Snape also fits the explanation that his mistreatment of others manifests itself when he is presented with reminders of his family. His first argument with Snape occurs on the Hogwarts Express en route to their first year. Sirius tells James that he comes from a family of Slytherins, but “maybe [he’ll] break the tradition,” then asks James which house he would choose (DH33). When James answers that he would choose Gryffindor, “where dwell the brave at heart,” like his dad, he mimes lifting a sword (DH33). In response, Snape makes “a small, disparaging noise,” which one could argue might not have been deliberately audible (DH33). Lifting an invisible sword for effect is a bold first impression for an eleven-year-old to make, and Snape certainly would never have done such a thing, so he probably thought it was extremely silly–and extremely Gryffindor. When asked by James, defensively, if he has a problem with that, Snape says no, but disparages the house, saying, “If you’d rather be brawny than brainy” (DH33). This moment defines Snape to Sirius immediately as the opposition–probably a soon-to-be Slytherin, just like everyone in his family has been. So Sirius stands up for his new friend, unfortunately escalating the encounter into the beginning of a lifetime of dislike, by saying, “Where’re you hoping to go, seeing as you’re neither?” (DH33).
When Snape is indeed sorted into Slytherin, likely making his interest in the dark arts and belief in Voldemort’s mission increasingly obvious over time, Sirius probably sees more and more of his family’s values in Snape. Despite coming from a wealthy family, whereas Snape was raised in poverty, and being one of the most popular students at Hogwarts, while one of Snape’s only friends is Lily, Sirius does not apply his wisdom to his interactions with Snape. He treats him cruelly, and Snape’s presumed retaliations could not have made it easy to stop. It is also likely that Sirius comes to this wise realization (about measuring a man’s character by observing his treatment of his inferiors) after his time at Hogwarts ends–perhaps not until he is serving time in Azkaban. The next time Sirius encounters him, Snape attempts to turn Sirius over to the dementors and refuses to believe (or care about) his innocence, and Snape has far more power than Sirius at this point, as a Hogwarts professor compared to a fugitive. Sirius continues to see Snape as a reminder of the values he rejected. Ultimately, despite his best efforts to rise above his family’s traditional sense of superiority, Sirius is still quick to fall back on antagonism as a method for handling disagreements.
When Sirius and Remus speak to Harry in Umbridge’s fire about Snape’s memory of being bullied by James and Sirius in their fifth year, Sirius tells Harry, “[James] grew out of it” (OP29). The same or similar could presumably be said of Sirius. Although he does not overcome his resentment enough to treat Kreacher with compassion, he learns (more or less) to work with Snape instead of against him, and he treats Harry and his friends like adults–a level of respect that they, as teenagers, crave. As he tells Harry a year after their meeting in the cave above Hogsmeade, “The world isn’t split into good people and Death Eaters” (OP14). Sirius does not always give “his inferiors” the consideration they deserve, but he always stands up for what he believes is right. Whether he fully heeds his own insight in his last days or not, Sirius imparts it to Harry, Ron, and Hermione, and they learn to apply that knowledge more effectively than he ever has the chance to. When they treat Kreacher with compassion, he abruptly begins to show them devotion akin to Dobby’s–“The quality of Kreacher’s cooking had improved dramatically ever since he had been given Regulus’s locket: Today’s French onion was as good as Harry had ever tasted” (DH12). The ultimate takeaway, perhaps, should be that it is best to treat everyone with compassion and respect as a matter of course, rather than only when cooperation is sought. If Sirius had done so, he might have lived to see Harry and his friends learn the same lesson; alternatively, perhaps the tragedy of Sirius’ death is the impetus that truly drives this lesson home for them.