The "Sansa reminds Sandor of his sister" motive that some people try to hitch to his character really just flies in the face of his actual attachments to her, doesn't it? Sansa reminds Sandor of himself. He sees the little boy who used to love knights in this girl who's been swept up by the same romanticism. He sees his abuser in her abusers, the much larger knight(s) beating on the helpless child. He sees how she is betrayed by every level of authority that should have saved her and remembers his father's neglect and Tywin and Robert's apathy for Gregor's crimes. He's protective of Sansa because he was Sansa.
And GRRM's design, that one of the strongest warriors in the series, a fearsome and cynical 6'8" guy who's "muscled like a bull" and has the face of death itself, sees himself in this soft and effeminate teen girl, and empathizes with her because he was an abuse victim too, is INFINITELY more compelling than "Oh yeah I bet she just reminds him of his sister," who he's never mentioned and who we know literally nothing about. Way to unnecessarily water down a character, you couldn't have ignored the black and white text more efficiently if you tried.
