Ok, I was thinking on “protected” as “having help and people who care for her” not a 24h companionship. My fault. She could be easy to find, and easy to “take” –so to speak- but with that sort of friends, I’m not so sure about being completely vulnerable. Unless a quick attack, like, “hey, Are you Belle? Yes? Nice to meet you, now, let me kill you”.
I don’t think that killing Rumplestiltskin in our world makes the killer the Dark One. Even having magic. In any case, maybe avoiding the curse could be a good starting point for a pirate to look for an alliance with Cora. Just guessing.
About Belle knowing that her beloved killed his first wife. Well, for sure I think she would confront him about that, but as I said, I think Belle is not a naïve-all-white character. Come on, she knows who she is in love with. At least, she should. One thing is say: “ok, stop acting like that if you want me to be with you”, but no one can change his past. So she would probably be scared, she would probably need some time to assimilate it, but that doesn’t mean she would take part for Hook.
But who knows?
I just hope Belle being strong enough not to be confused by the situation and Hook being twisted enough not to act like a quick killer.