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…)
So even some of the good stuff she has done is shaded over with suspicion for the audience now.
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Keeper of Belle's Gold magic, sand dollar, cloaks, purple FTL outfit, spell scroll, library key, copy of Romeo and Juliet, and cry-muffling pillow, Rumple's doll, overcoat, and strength, and The Timeline. My spreadsheet: https://drive.google.com/file/d/0B6r8CySCCWd9R0RUNm4xR3RhMEU/view?usp=sharing