Throught the first read of the series I really did not take to the Hound. But with each reread I liked hime even more. He has turned into one of my favorite characters. He goes against the typical arch type. I think that he battles with the image of being a "knight" and that of his brother. He goes out and saves Sansa, i think that his action were not just saving the future wife of the King. He has feelings for Sansa. As he saod to Arya, Sansa gave him a song and he should have taken it. He said that he should have saved her (the knight in him) then he says the he'd rape/ kill her (i think) (thats Gregor's influence).
As far as his scares I believe that Gregor mained Sandor. As Jon said, fire is life and death in the north. Well to the hound fire is death and hell. I do hope that the Hound and the Mountain will meet once and for all, with the hound being the victor. Also as a twist, I think that Sandor and Sansa will in the end marry or something on that path. Sansa is filled stories of knights and what not. Sansa falls in love with Loras as the "perfect knight" in the realm, yet the perfect knight was under her noise all this time, the hound.