I was having this problem at the end of the Fable 3 Darkness Incarnate quest where you're supposed to lead Walter into the light. He wouldn't grab my hand. I searched everywhere for a fix. All I could find was "start a new game." Well, fuck that! I'm almost to the end of the Road to Rule! I hadn't saved my game after finding the glitch. I loaded my game and it took me back to where you come across those shadows with the glowing red eyes for the first time. I pushed forward and when I got to the place where I'd initially encountered the glitch, I found no problems.
So, hopefully you haven't saved you game. Reload, fight your way through the cave again.
Hope this helps!
Sir Walter Beck Walter Fable 3 Darkness Incarnate Glitch
Fable 3 Walter Glitch
Walter won't hold my hand
Can't get walter to hold my hand