Cain is definitely a creeper but I can see his viewpoint. He has never once thought of Aria as family and, more often then not, tried to destroy all familial connections to her and her mother due to class prejudice. Seeing him suddenly attracted to her isn't surprising at all since Aria is stunning. However, he still deserves to get his ass handed to him for the b.s. he pulled in the previous timeline. No mercy, Aria!