TL; DR: Han var en del av "idealized father figure" -temat i serien inspirerad av Rowlings stackars relation med sin egen pappa.
Det enda officiella ordet jag har kunnat hitta är följande, från en intervju där JK Rowling pratade om olika sätt hennes eget liv och bakgrund påverkade hennes skrivande i HP-böckerna.
Rowling delved into writing at an early age, but her thoughts about love, death, heaven and hell were tested when her mother was diagnosed with multiple sclerosis in 1980.
"She had a very virulent form of the illness and at that time there were no drug treatments at all," Rowling said. "And they said 'well you've got multiple sclerosis, see you.'"
The illness devastated Rowling and her sister, and strained her relationship with her father.
"I was very frightened of my father for a very long time," she said in the 2006 interview. "...I also tried desperately to get his approval and make him happy, I suppose, and then there came a point quite shamingly late in life where I couldn't do that anymore, and so, I haven't had any contact with my father now for a few years."
Rowling's far from ideal relationship with her father inspired idealized father figures, like Hagrid, Dumbledore, and Sirius Black, in the series. She says the absence of any meaningful relationship with her father and the loss of her mother have been the two of the most important influences on her writing.
"I had been writing for six months before she died and, the weird thing is, the essential plot didn't change after my mother died, but everything deepened and darkened," Rowling said. "Harry was always going to lose his parents. And it was always going to be a quest really to avenge them, but to avenge everyone against this, this creature -- this being who believes that he can make himself immortal by killing other people. So that's, that that's something I'd created before she died, but yes, its seeped into every part of the books. I think, in retrospect now I've finished I see just how much it informed everything."
Den enda andra informationen som Rowling har gett ut om Sirius i efterbokssamtal är hans födelsedag 3 november , som hon lovade att berätta för fans om tillräckligt med dem stödde sitt favoritfotbollslag - de gjorde, så hon gjorde upp ett datum för dem. Sann historia .