If there were scales between gods and humans, every time a person saved a living creature, no matter what it was, there would be a price. Buckbeak had bought Sirius two years. If someone were willing to try, they could weigh more creatures too—for instance, how much lifespan could be gained by saving a Runespoor? But only if someone was willing to make that bargain.
When Sirius had first escaped, he had wandered for a time to evade capture. All sorts of rumors spread everywhere; some people even believed he had gone to kill Harry Potter.
At the start of Harry's third year, he had seemed uneasy. Perhaps he had heard that rumor. It was not until they reached the Shrieking Shack, when Snape had followed them there looking for trouble, that the misunderstanding between him and Sirius was cleared up.
Women might fall in love at first sight, but men did not immediately turn from enemies into close friends, much less become inseparable companions—especially when the other person was the "killer" Harry had once feared. If Sirius had died then, Harry would have felt sad at most. Sirius would still have been a stranger to him.
Two years later, Sirius was struck by Bella's Killing Curse during the chaotic battle at the Ministry of Magic. By then, Harry knew Sirius well. He had even regarded him as a substitute for a father. His memories with Sirius had been happy, so losing him hurt all the more. The pain had even driven him out of his mind. He pestered a ghost with questions about life and death, questioned Nearly Headless Nick until he cried, and spread the matter throughout the ghosts. Aside from the Bloody Baron, who remained as gloomy as ever, even Hufflepuff's Fat Friar sighed endlessly. That summer