I liked this question and enjoyed reading the responses. When I was making my choice I could actually find cause to put her in all the categories. But, I chose victim. I dislike the Kay character but when I think back on the scene where Michael approaches her after all those years, Kay is very hurt and is crying. She asks Michael why after all these years and she tries to be rational when she explains to Michael that its too late. But he comes off with this "I love you" "I'm working with my father but his way of doing business is over and even he knows it" - was Michael's way of getting what he wanted. I think I read in one of the books on the making of the Godfather that there was a part in the script that actually had Vito presurring Michael to put Sicily behind him and get married as it was his responsibility to start a family.
Anywy - good topic.