I've never really hated any character, though there certainly are characters that I never cared too much for, i.e. Nina and Rolo. In general, characters that are "unlikable" in this series tend to fall into two categories for me: 1) sympathetic (i.e. Suzaku), and 2) not worth my time (i.e. Luciano). Then there's Nina who I want to give my sympathy to, but the story refuses to give us any backstory. -_-

If anything, I came to like Rolo more when he died NOT when LELOUCH accepted him but when ROLO accepted himself. I go gushy for self-affirmation.