When we last left the group in Storybrooke, Emma had sacrificed herself to the darkness and took the power of the Dark One, leaving behind the dagger with her name on it.
Emma had spent the better part of the second half of the previous season fighting her dark side, and now with her taking in the darkness she will be facing a real struggle. Creator Edward Kitsis said of the struggle:
What happens when [the darkness] mixes with the lightest magic of all, and will Emma have the strength to fight it? Becoming the Dark One allows you to have the freedom to have no inhibitions, we are going to be exploring love and what happens when you use it as a weapon and what are the things that it makes you do. In the past, we’ve said love is the most powerful magic of all. It makes you do many things you normally wouldn’t think you would.
Once Upon a Time co-creator and executive producer Adam Horowitz added
How a Dark One manifests is specific to each person who takes on the mantle. Emma will have her own unique spin on what it means to be a Dark One.
Emma has been fighting the darkness inside her since The Queens of Darkness and Maleficent's daughter, Lily, arrived into town. The dagger could be the perfect excuse for her to release her inhibitions and just give into the darkness inside of her that her parents had tried so hard to snuff out.
The tie in with Camelot this coming season is in the hope to save Emma, as they have to begin their search for Merlin. this may call for a new savior, but I wonder if that could mean Lily? They had been polar mirrors of each other growing, as Lily had originally been given Emma's darkness. If Emma has given into it, maybe that means that Lily, who is staying to get to know her mother, will become light. Only watching the new season will tell.
It definitely looks like the group will have their work cut out for them, as she apparently does make her way back to Storybrooke (that's Granny's diner) and if she has control of her dagger there is no telling what havoc she will reek on the town, especially those who she could blame for her unhappiness growing up.
With Camelot and a new villain in the woman that has always been the hero, season 5 is shaping into being the best season yet
Once Upon a Time returns September 27th on ABC.