4. The writers and directors of the Big O came up with Dorothy's character at the very beginning, whereas Angel was a later stipulation.
Something I find interesting, however, is that if you look in the artbook, one of the early concept drawings for Dorothy is very close to what Angel ended up looking like. Also, how do you know that they didn't have Angel in mind from the beginning? I ask this in all seriousness, because I really don't know much about what the writers/directors have said regarding their plans for the show.
5. Dorothy lives with Roger and is therefore a more established part of his life. If Angel moved in, Dorothy would have to leave. Does that seem likely to any of you? Or do you think it is more likely Angel and Roger would not move in together?
6. For that matter, does Angel seem like the type of woman who moves in with anybody?
I can't see Angel living with anyone.. currently, that is. I have my theories about her past. But the way she is now, no, I don't see her picking up and moving in with Roger, even if he were to reciprocate her feelings. She's accustomed to being able to come and go as she pleases, and I think that living with someone would make her feel restricted. Plus, I think they'd fight over the bathroom too much.
"Angel! I need to do my hair!"
"Then you shouldn't have slept so late!"
"But I have a client!"
"So do I. By the way, you're out of hair gel."
Etc, etc.
But even if Angel moved in, I don't think it would be that Dorothy had to leave so much as she would likely choose to. Roger would never throw her out, even if he ended up choosing the other woman. He chose to protect Dorothy, and I think he's got a strict enough sense of nobility that he would hold himself to that. Although I guess that he can do that even without Dorothy living there anymore. I don't know.
8. Angel is a femme fatalle and they usually don't end up with the hero at the end; at least, not in comparison with the 'nice girl', who usually mends the heroes shattered heart after the femme fatalle lets him down in some way. Femme fatalles sometimes end up with the hero, but their nature usually dictates they betray or leave him; even if they love him.
I think the only thing you could count as Angel letting Roger down would be not saving Dorothy from Alan, but he never finds out about that. She does betray him quite often for the first half of the series, but has a noticeable change of heart after that. So I don't think that Dorothy has much "mending of the heart" to do in regards to Roger. It's more that she has to break past that big ol' wall of denial he's put up. He already realizes that he doesn't love Angel-- but he also won't admit that he feels anything for Dorothy.