Not much to add to this one, frankly:
Question 59 – Have you ever written a character so offensive that you hated or strongly disliked them?
So far in my entire series, I’ve only had one character whom I truly dislike. Of course, since I wrote him, I’m the one who made him unlikable and reprehensible, so I can’t really say that I hate him — more that he’s serving his purpose in the story. Everyone is supposed to hate him. It’s also my job to humanize him, and to understand how and why he took such a wrong turn in his life; I don’t like writing flat villains, and unlike the readers I can see how he could have turned out better. So really, there’s only distaste and pity and my plans for his demise.
The War of Memory Project 