WARNING: Slight spoilers for This Is Not a Game, by Walter Jon Williams.
Which unforgiveable did the author pull?
Reader manipulation. He sets up a secondary, very probable, betrayal scenario toward the end of the book, then proceeds to completely over sell it. But it flops, because in the end, the secondary betrayal isn't there. Nothing is. And the main character blows it all off by saying "crazy, complicated stuff like that only happens in the fiction I write, not in real life."
He sets us up by KNOWING that as fiction readers we're EXPECTING for there to be something more. But there isn't. Not only did that make the ending totally flop for me, but it pissed me off to the extreme. If he didn't want to make a crazy, complicated ending, then just don't make it that way. Don't set things up to look like it and then (essentially) point your finger at your reader-audience and say "Ha, ha. Stupid you. You fell for it." I read books for the fun stuff. Not because it's real. If I wanted real, I'd pick up a non-fiction book.
Augh!
Sorry, guess I should just shut up now. It just totally torqued me.
Don't worry about the suggestion, Sigyn. I had been planning on reading him anyways, and this book ended up being a shorter one than the one I had planned on picking up. Like I mentioned, I liked the rest of the book quite a bit. It was just the end that totally ruined it for me. I might pick up another one by him in about 10 years or so. It might just take that long for me to get past this. I'd still take another suggestion from you any time.