A/N: I don't actually think that Emma can fall so deep but the idea of dark!Emma just intrigues me so this happened. It's kinda spoiler-y so read at your own risk!

Part 1 No light, no light...

Darkness was a curious thing. It had the tendency to sneak up on a person without notice and then it was there, possessing every single part of the body, the mind, the soul. She had been warned of this. Someone she once cared about deeply had told her so. It hadn't mattered to her then because she was her own master and decided her own fate and darkness was not what she would've chosen then. Now though? Darkness was not only part of her, she was darkness in everything but name. There was rage coursing through her veins, and fire. There was power and lust and a burning desire to destroy. She had chosen darkness and she would keep choosing it because it just felt so damn good. There were people out there who wanted her to turn away from it, she knew that, but those people had been part of what had made her turn dark in the first place. Her life had always been a series of betrayals and losses, of trying to see the good in everyone and to hope, only to be disappointed again and again. She'd thought she'd found it, her happiness, her home, her family. And then they had just proven to her that trust was dangerous. She had trusted them and got burned for it. Lies. Nothing but lies everywhere. Were they really that surprised that the darkness had found a way in?

She had fought it at first, she really had. She had tried to be good, had tried to hold on to the hope that everyone always talked about, had tried to do her duty as the saviour. She had brought back the only friend she ever had growing up and had reunited her with her mother; there she'd been, her friend, Lily. Her opposite. The girl with all the potential for darkness. And here she was. Emma, the girl with all the potential for light. She had to laugh. Life was not that simple, no matter what her parents thought.

She'd tried to stay true, had brought someone else another happy ending but to her bringing Lily back had only caused more pain, more loss, more lies.

Emma had always lived a life in the grey zone between black and white. Grey was her friend, grey was what got her through. Stealing, running away, conning, those were her constant companions out there in the real world, the world without magic, without heroes and villains, where happy endings were not just brought on through hope, where love was rare and betrayal an everyday occurrence. She'd thought she'd experienced love but had found loss instead. She'd thought she'd found a home once but had lost it instead. Sometimes she marvelled at how she had stayed on the path of light for so long when light had been only too rare in her life and she always lost it again. It had really always been simply a matter of time until she strayed from the path. Potential for goodness, her parents had told her. Her potential for goodness ran about as deep as theirs and as she had had to find out that was not as deep as they'd always pretended.

Yes, her magic had been light, there was that. But now, oh now her magic was more powerful than ever before. There was hardly any effort involved in it, it was as if the will to stay good had been a boundary that kept her from reaching her full potential and now that she didn't care anymore her powers were magnified, dark, strong and unyielding to the influence of others, bending only to her will and her desires.

"Mom!"

Henry. Her son. She'd loved him once, maybe she still did deep down.

From her vantage point on top of the hill enclosed by trees she could see him running towards her when she turned her head but she didn't care to see him so she faced the town below instead. She could feel him stop right outside the force-field surrounding her but she didn't turn to look at him. Yes, she had indeed loved him once but now that love was of no consequence anymore. He'd brought her to this town to brake a curse and bring back happy endings. She had done that. She had given him her heart, loved him, cared for him in turn but he had chosen Regina, he didn't need her. Her love for him had become something he took for granted, he had thrown her heart away, at least that's what the darkness told her, that's what she told herself so she had a reason not to care for him anymore.

"Mom!" Henry shouted again and Emma finally turned around, meeting her son's eyes that looked back at her, scared, lost even. His father's eyes. Maybe Henry had always been destined to betray her just like his father had. The thought hurt but it was a dull pain, hidden deep below her suppressed emotions.

"Mom, please!"

Emma could hear the quiver in his voice but it left her cold. There was only one thing on her mind and it was darkness. Always darkness. Her powers were strong but oh, how strong would she be if she finally got hold of the one thing she desired most right now. She could feel it, the dagger. It was made of darkness and it had fuelled her darkness, they were connected already. Gold had done everything to plant seeds of evil in her, had watched them grow into dark flowers that consumed her and now she craved more of it. She wanted to feel the power of holding the most powerful dark instrument in her own hands, wanted to be its master, wanted to own it. She could feel the blade and she knew it was getting closer.

Noises from the woods momentarily shook her from her thoughts. More people were approaching and when she searched the trees, she suddenly found herself looking into an ocean. Her heart leapt, something in her reminding her of the feelings she'd had for the man standing there. But then she remembered his betrayal and it was like her heart got ripped and crushed into ash, drowning her of colour and emotion, drowning her of every single happy memory she had ever made with him, turning them dark and twisted and revealing them as the lies they were. Everyone else's betrayal she had been able to suppress, live with, at least a bit. But his? His betrayal had been the one that had sent her tumbling over the edge where she embraced the night like an old friend hoping she would get swallowed by the dark abyss.

She'd believed that she meant as much to him as he meant to her. He'd basically told her so. He'd told her she was his happy ending. But apparently that had not been enough for the pirate. As she thought back and remembered what he'd done to her, how he had toyed with her, rage started to roar in her like a beast that wanted to be let out, set free to destroy and wreck havoc, kill. Sparks began flying around her, dark smoke swirling and sizzling like electricity, illuminating her in a dark purplish glow, beautiful and menacing at once. She turned her head to look at the two people standing at the edge of her force-field and she could see the fear in her son's eyes, a pang of regret flaring up inside her. Then her eyes found Killian's again and the regret disappeared. He looked worried, maybe even scared but she didn't care. With an angry scream - her usually calm demeanour long gone - she sent a wave of dark magic flying towards her former lover.

Killian reacted quickly, jumping out of the way just in time and even in her rage she could still see the surprise on his face. He seemed not to know what had driven her to attack him, seemed not to know that she knew, that she had seen. He always talked of honour and good form, yet something had driven him to throw both overboard in favour for the other one. Lily. She should never have brought her back, should never have attempted to bring happy endings back. She should've held on to her own happy ending and ran away with it. She should've… oh, what good did it do her to dwell on the things she should have done. It would not change the past, it would not change the future. She had darkness now and it was all that mattered.

"Emma!"

His voice broke, worry etched deep into the sonorous tones that usually soothed her, that usually made her want to run into his arms and hold him tight. There was none of that now nor would it ever be again.

"Emma, please! Let go of this madness!" he begged her, trying to step closer, trying to break the spell that enclosed her completely.

A laugh escaped her lips and she had to smirk at his weakness. What had possessed her to fall for him? She must have been weak herself but now, now she was strong and she would not give in.

"This isn't madness, Killian," she spat, "it's what everyone has driven me towards. Don't you see? This is who I really am, I have never been more powerful, more alive!"

"Darkness is a funny thing, isn't it…" he smiled sadly at her. He knew darkness only too well, he knew what it was like and his biggest fear had come true. He was losing her to it, he was losing her to Gold, the man who had once before taken his love from him.

"It is indeed…" Emma whispered to herself, her palms burning with energy, wanting to get revenge on the man she'd loved. Maybe wanting revenge meant she still loved him. She should feel nothing but she did. The pain was always there like a thousand needles piercing her heart, making her bleed from the inside out. She liked the pain, she knew pain. And this pain fed the monster inside her, made it grow bigger and darker, more powerful and she itched to release another spell to show him how he'd betrayed her, to make him feel the pain she felt.

Instead she balled her hands to fists quenching the sparks and calming herself. The fire still pulsed through her veins but she needed a clear head. There was only one thing left for her to do and before she did, she wanted Killian to know that this was his fault, that he had driven her over the edge.

Straightening her back, she stepped forward, slowly, one foot in front of the other, her eyes hard as steel. She watched him watch her, saw the hope flare up in his soft eyes, in the way he shuffled on his feet, the way he scratched his ear absentmindedly, the nervous tick she used to adore so much.

"You've got something I want," she whispered, stopping on her side of the force-field only a breath away from him. She could smell him, could feel his warmth and her body wanted him, craved him, desired him as it had from the moment she had first laid eyes on him in the Enchanted Forest so long ago.

He frowned at her questioningly but made no move to give her the instrument hidden inside his jacket. She could feel it pulsing there, emanating its dark nature to her, calling her. With a flick of her hand the dagger finally found its home in her palm and as soon as the handle touched her skin a new wave of electricity rushed through her igniting the force of her magic tenfold again. There was still another name written on the blade, she was not yet its master but she could feel that the blade wanted to be hers as much as she wanted it to be hers.

She heard her son gasp to the right, was aware of her parents figures showing up behind Killian, her mother a look of fear and failure on her face, her father looking uncertain, lost. She saw Killian reach out for her, a silent "Emma, no" on his lips, saw his hand being repelled by the spell around her, saw the pain flash across his face. She also felt her new strength coursing through her. She could feel every particle, every atom in the air, felt like she could split it with a single thought of her mind, a single flick of her hand. The world was hers and hers alone.

"Emma," Killian's voice rang through to her, bringing her back to the people surrounding her and she met his eyes once more.

"What?!" she exclaimed, "did you think I wouldn't notice you had the blade?"

Killian shook his head but Emma wasn't going to let him reply.

"Did you think you could sneak up on me and kill me so you could be with Lily?!"

She growled her friends name through gritted teeth, watched Killian's reaction, wanted to see the truth of her words in his eyes but what she saw was confusion.

She'd seen him kiss Lily as fiercely as he used to kiss her and it had shattered her world into pieces, had destroyed her more than anything else because he was the one who was supposed to stand by her, be her rock and her solace and he had betrayed her.

"I saw you," she disclosed in hushed tones, the hurt pressing through the darkness, the emotions more overwhelming that she thought they would be.

"Saw what, love?" he asked still confused, his eyebrow raised, eyes searching hers questioningly. His endearment pained her now, wasn't the usual soft assurance that he cared for her.

"I saw you kiss her. Just be honest so we can move on." She straightened her back again, stealing herself, becoming iron, building up her wall higher than ever in an attempt not to feel a thing. Not feeling anything was a good option when what you felt was only pain, she remembered her own words from so long ago.

She looked at Killian then, finally wanting to see his reaction, see him admit to it. What she saw on his face, however, was surprise, confusion, astonishment. Her superpower was still fully intact and she could see no lie in the look on his face, he had no idea what she was talking about and it confused her. Had she been wrong? Had she been tricked? Had it all been a construct of Gold's plan for her to turn? None of it mattered now, the damage was done no matter if it had been Killian or Gold's doing, she was too far gone, too shrouded in darkness to turn around.

Emma shrugged her shoulders then. "It makes no difference anymore."

"It does to me, love. I would never betray you…" He paused, scrutinising her and it seemed as if he came to a decision then as he squared his shoulders and reached out for her again, stopping his hand just before the force-field.

"I can see that you will not turn from the darkness that possesses you but I will not turn from you. I know the darkness and for you I will willingly slip back into it. I brought you the dagger in case I found you like this so I could give it to you and prove that I am yours forever and in whatever way you want me. What do you say, love? You and I can bring down the Dark One and give in to the night together, rule the seas and take whatever we want."

The man staring at her now was no longer Killian Jones. Somewhere during his little speech he had revealed his true nature to her, Captain Hook, the feared ruthless pirate who wanted nothing more but revenge and took what was his right without fear of consequences. His eyes had grown darker, hooded with the darkness that she'd seen before. She had always been attracted to his revenge driven persona but now that she felt her own dark nature, his attracted her even more. The smirk on his face revealed to her that he knew her answer, knew that she could not resist him like this.

A new fire ignited in the pit of her stomach. She no longer cared if he had betrayed her or not. What she felt now was not love even though it had once been that. It was now simple desire and the want for their bodies to crash and be one, to chase the darkness together, to destroy together, to make everyone fear them, to care only for themselves and no one else.

A smirk of her own appeared on her face and she gripped the dagger tighter, her hand reaching out to grab him by the collar of his leather jacket. With one quick jerk she pulled him through the force-field and to her, the dagger suddenly at his throat, a threatening look on her face.

"If you ever dare to even think about betraying me I will drive this blade right through you heart, do you understand?" she growled through gritted teeth, the blade cutting into the thin skin of his neck ever so slightly, a trickle of blood accentuating her point. Behind them, she could hear Mary Margaret gasp, could see David grab his wife around the waist and holding her close, saw Henry run towards his grandparents and she still did not care. Hook grinned at her, wiggling his eyebrows and cocking his head sideways, deepening the cut as a result.

"I would not dare, love."

She nodded once, turned him around, still holding the blade to his throat and looked at her family. She meant what she had said to Hook but she also knew that no matter what drove her, he would always be part of her. He was good for her when she was good, now that she was dark, she needed him dark as well but if he betrayed her, he would not live to tell the tale. It would be the hardest thing she ever did but she knew she would do it nonetheless. With that thought in mind, she met her father's eyes, then her mothers and her sons.

"Don't try to find us," she told them, waiting for the little nod she knew David would give her. Her father felt responsible for what she was now and when her father felt responsible she knew he would try anything to make it right again. This was all he could do right now so just like she thought he would, he nodded once. She didn't see the look he exchanged with Killian. Finally, with a flick of her hand, the force-field disappeared, black smoke started circling around her and Hook and then they disappeared.