Well, Martha is a good person. I think a lot of the Doctor/Rose fandom was quick to hate her because she had a crush on the Doctor. I never cared for that part of her storyline, but I always really liked Martha. If Martha had known the truth from the start, I don't think she'd ever have fallen for him at all.

Thanks. Onna just felt like a good way to tie people together. Rochester was so mean to Tim, too, it felt like a good extension to have Martha being worried about him.