The problem with her saving Marian’s life is that we also saw her tell Sidney that she had to get rid of Marian in a way that cast no suspicion on her. So saving Marian’s life…could be a way to give her an alibi later. (You know, like giving Belle the fake dagger gave Rumple an alibi later…)
That’s a valid point. I have to wonder though whether Regina will actually carry out a scheme against Marian after coming so far in s3. Like I wrote, she’s certainly still tempted by dark magic. And as you say, she’s employed Sidney to do her dirty work. However, I’m still more inclined to give her the benefit of the doubt. As I mentioned, Henry’s going to be helping his mom out, and there’s no way Henry would agree to let his mom kill Marian. I for one want Marian to live, and I also have this suspicion that her presence is going to help fuel Regina’s redemption further. Regina may be convicted in the end. (That may be wishful thinking on my part, but I think Regina has come too far for the writers to put her all the way back at square one). While Marian may die by some other means, I hope Regina won’t be even indirectly responsible for it.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy