Sirius is very good at spouting bits of excellent personal philosophy, but he does not always live up to them. For instance, he says in Goblet of Fire that if you want to know what a man is really like, ‘look at how he treats his inferiors, not his equals.’ But Sirius loathes Kreacher, the house-elf he has inherited, and treats him with nothing but contempt. Similarly, Sirius claims that nobody is wholly good or wholly evil, and yet the way he acts towards Snape suggests that he cannot conceive of any latent good qualities there. Of course, these double standards exist in most of us; we might know how we ought to behave, but actually doing it is a different matter!
Sirius is brave, loyal, reckless, embittered and slightly unbalanced by his long stay in Azkaban. He has never really had the chance to grow up; he was around twenty-two when he was sent off to Azkaban, and has had very little normal adult life. Lupin, who is the same age, seems much older and more mature. Sirius’s great redeeming quality is how much affection he is capable of feeling. He loved James like a brother and he went on to transfer that attachment to Harry.
→ JKR. (via courtesiren)