The Darkness

The Darkness is an ancient being which, eons ago, did battle with the powerful sorcerer Merlin, and soon found itself tethered to a human to form the Dark One, enhancing said human with magical powers. However, in this form, the darkness could be controlled by a dagger. If this dagger is used to kill the Dark One, the murderer must take their place, as is what happened to Rumplestiltskin when he murdered Zoso. The darkness consumed Rumple's heart until it had to be removed, only to end up tethered to Emma Swan instead.

Before the Curse
The sorcerer Merlin battled the Darkness a long time ago, and managed to successfully tether it to a living being - the first Dark One - while binding it to a dagger, which could control it.

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Season 2
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Season 3
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Before the Second Curse
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Season 4
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