So I've constructed an early theory:
So, Merlin tells Emma not to draw Excalibur. My guess is that he knew she'd become the Dark One, therefore attempting to draw Excalibur would kill her (as it did with that one knight), or if she had not taken the Darkness on, then she would have been worthy and would've kept Arthur from becoming King which Merlin didn't want. Now, my guess is that Excalibur will obviously have a very huge role to play in the fate of the Darkness. This role is obviously unknown.
We should start by asking the question: Why did the Dark Ones all want to remove the Dagger from themselves? According to the Apprentice, all Dark Ones tried to, and all of them failed. Gold explains that freeing himself from the Dagger would "fix" his heart problem somehow, but that doesn't make any sense. Since his heart blackening is from all the dark deeds he did, and according to him, the Dark One would still live on, but Rumplestilzkin would be no more. Basically, the Darkness would take over his body. So, why would removing himself from the Dagger fix anything? My guess is that the Dagger is some kind of seal. Made to prevent the Darkness from ever growing too strong. Anybody could control the Dark One via the Dagger, and one could kill the previous Dark One and become the new one. My guess is that this would keep the Darkness from accumulating too much power, for if allowed to run freely, they would commit a crapload of evil deeds, but if they were under control then the Darkness would stay at a controlled pace. Killing a Dark One and taking on their power would reset the Darkness based on the heart taking on that power. The reason it got so bad was because Rumple went so long without being controlled and without giving up his power. Because of this we know that Rumple almost succeeded in removing the Dagger. Somehow, he clearly knew the spell that none of the other Dark Ones did. Where did he get from? He couldn't have simply known it. Doesn't make sense. He had to get it from somewhere (my guess is Camelot).
So, what would remove the Dagger? My guess is that removing the Dagger would render it inert, and the Darkness could roam free. I'm assuming that because of this, the Darkness is manipulating the Dark One, and it's not really up to the Dark One. It explains Gold's "ghost" haunting Emma and still explaining abilities to her.
So the real question becomes: what role does Excalibur play? I can't say. Either the Dark One can only be killed by Excalibur, or something. This may explain why Emma hates everyone so much after they come back (aside from Dark magic evilness). She claims they did something to her, doesn't say, but the Dagger still exists. I also have a guess that they may try to convince Henry to write Emma into the book and trap her there. Or trap the Darkness there. I mean, all he did was break the quill. Gold states that a quill can be constructed from enchanted wood. Plus, we know that the ink is pure darkness (which I still don't get, but maybe I missed the explanation. Twice), so they could just take Emma's blood. We know Henry is the Author, and he has the Heart of the Truest Believer, so maybe that makes him a Super Author?
I dunno. Just spitballing.
Wait, really? You should probably watch Frozen, then. I imagine it would make a lot of things make more sense.
It made perfect sense to me. The movie is really just backstory that I really don't need at that point. I mean, they explain enough about it: Elsa put Arendelle in eternal winter; Hans tried to take advantage of Anna; Their parents died. Really, you can treat the first arc as a sequel, but it's done in a way that the movie isn't necessary. Especially since it primarily focuses on Ingrid and the other OUaT characters anyways.
I'm pretty sure he got that name prior to KH.
Yes he did. I was incorrect in my previous post then.