For me, it was Khellus. He is by far one of the most interesting characters I've read, but
Also, book spoiler and a potentially graphic... Seriously, heed that last part, I'm sharing a specific instance that messed me up for a few hours, as far as I'm concerned, the Red Wedding doesn't have rust on this scene...no, don't click it to satisfy your morbid curiosity! Don't do it!