Yes, "cut my own throat" Dibbler was a truly classic character that fit so perfectly into the Discworld. Often his role was a cameo in the books, but it was the cameo you looked for.
I can honestly say no. I've been a big believer that all characters must fill their role in the story, and that doesn't change. The character I really like that's meant to die? Bye-bye. The character I suddenly realized is more interesting than the role I gave him? Oops, maybe save it for a side story. The closest I've come to this is planning. I created two jerk characters in story one of a series in my head, and I'm going to have them come back later to be demi-redeemed. They're still jerks, but just because someone is a jerk doesn't mean he can't be a nice person. In the case of these two, it's their jerkitude that makes them nice later on. They don't really understand my MC, and because of circumstances change the pre-conceived notion they have of her into a different, more sympathetic pre-conceived notion. Forgiveness and hugs all around.
Yes, in my story I have an antagonist named Kwame who many people seem to side with everytime I tell them my rough draft of the story. He's a young runaway slave who stumbles upon a remote village upon escaping and the MC distrusts him for believing that he could be a spy. Kwame manages to woo everyone with his natiral leadership and fighting skills which the MC sees as a threat to his ambitions of becoming leader. The fact that many readers still side with the MC makes things interesting since it keeps things from being black and white.
