Sirius Black had many flaws. From what we know, as a teenager (and, to an extent, later in life), he was arrogant, mean, reckless, hot-headed. But do you know what he also was? He was someone who appreciated the fact that Ron lost a pet because of him and his family couldn't afford to buy him a new one so he gifted him a little owl. Deeper still, he must have thought of Ron and what internal chaos he must have been going through, finding out he'd been harbouring and caring for a murderer for the past three years and he extended a simple gesture to say 'I see you'. He was the kind of person who asked if Ron was OK, after he broke his leg and passed out, even though he was in the midst of escaping a Dementor's kiss and going through the devastation of not having his name cleared. He was someone who, although he'd only just properly met him and escaped 12 years of toture and suffering in Azkaban, he offered Harry a home without a moment's hesitation. One of his take-aways from his wrongful imprisonment was the fact that he missed 13 years worth of birthday presents for Harry and he risked his life to watch his godson play Quidditch, like the proud Godfather he was. He didn't kill Peter Pettigrew when he had the chance, simply because Harry asked him not to. The man was nowhere near perfect, but there was a good, good heart beneath it all.
