When Once Upon A Time Season 5 premieres later this year, it won't come as a shock to find Emma Swan in an extremely dark place — the darkest place there is, in fact. The former Savior sacrificed herself in the Season 4 finale in order to preserve Regina's happiness (and likely save her life in the process), and now we've got a real problem on our hands. Unless the gang manages to find Merlin — the one wizard who can get rid of the Dark One once and for all — then Emma has no chance of being restored to her former self, and that's a pretty scary prospect for everyone, I'd say.
Of course, as I've posited before, Emma's dark turn does represent the fulfillment of a fate she only narrowly escaped (and only by her parents doing something pretty awful to make sure of it), so it's not completely surprising that this has happened. Nor is it surprising that Regina, to whom Emma is so indelibly bound, is now in the position to play the hero she never managed to be. It's a classic tale of role reversal and one that should be amazing to watch. And while I can't wait for Emma to get back to her old self, I also recognize the potential for the Dark!Emma storyline and am looking forward to seeing it explored.
The reason the whole "Emma as Dark One" thing makes so much sense is that never has a character had reason to use the powers that come along with the title. Sure, Gold blackened his heart with countless evil deeds over the years, but his motivations were based on one thing only: to protect — and then to locate and win back — his son, and frankly, that motivation got swallowed up by the selfishness and greed that overtook him. Rumpelstiltskin was a coward before he became the Dark One, but his new power didn't suddenly change him into a noble, courageous warrior. Instead, that power made him more cowardly than ever, as he resorted to using it to get his way at all costs and to inflict pain on those who failed to bend to his will.
When it comes to Emma, the product of True Love and possessor of Light Magic, we know one thing: she doesn't walk away from a fight. While the Darkness is now tethered to her, it doesn't automatically take away the goodness it's now overshadowing. Just as Rumpel maintained much of his earlier character for a period of time, so will Emma, and it may be that fact that saves her — or that becomes her undoing. The battle between light and dark within her will be monumental and one that only she can wage, and it's too early to say which side will win — at least not without outside intervention.
Emma as she was loved fiercely, protected those she loves, and would sacrifice everything — her whole life, even — if it meant she could uphold those ideals. She's tough, she's stubborn, and, well, she's the Savior. But the Dark One has its own powers, and that's the ability to corrupt every good thing in whoever it touches. Emma's love for Henry, her parents, and even for Regina could become twisted or could motivate her to do dark things unlike any she would have ever previously contemplated. And considering how much love Emma has within her, the Dark One has a lot to work with, and that makes her scarier than ever. We've just gotta hope she pulls through (and I'm pretty sure she will).