based on the filming spoilers of Colin on the roof of the library. Speculation.
She has already seen him like this, once. On his back, on the street at the Town line of Storybrooke - bloody, battered, unable to move. Hit by a car after he'd shot Belle. His ribs were broken, and he was in pain, but at least he was conscious and in his right mind enough to greet her with a flirty quip.
But now... he looks different now. Lifeless. His face is white, his eyes are closed, and a thin line of blood trickles from his right ear. His limbs are sprawled out in strange angles, like of a broken toy, carelessly thrown in the corner by its bored owner.
And isn't that exactly what he is, what he has been for a long time? A toy, picked up and tossed aside to her liking, especially in those last weeks. He has tried over and over again, to the point of annoyance, to convince her that the darkness is not who she is, who she needs to be. He has tried to play any trick his sneaky pirate brain could come up with, but the darkness has always kept the upper hand. And she is fine with it. The stupid idiot, he couldn't understand that she – they – could perfectly well live with the darkness, even use it to get everything they ever wanted, but he of course wouldn't have any of hat. He insisted that he didn't need any of that.
And now they are here – she's kneeling on the concrete floor in front of the library beside his broken body, her hand on his front, the other one on his chest, above his heart. For a moment, she remembers how it felt to hold his warm, pulsating heart in her hand, full of life. Now she can't feel anything, there is no heartbeat.
"Killian!" she hisses breathlessly and slaps his cheek. "Damn you, wake up! Wake up!"
But he remains lifeless. She doesn't believe it, she can't believe this is how it's going to end. She had plans, so many plans. Plans to finally have the life she deserves, finally have a family of her own, with her son, with him. And he dares to fuck with her plans? She hears his angry voice reverberate in her head, from a long time ago: You need me alive!
"Bastard!" She punches his shoulder, roughly. He doesn't move. "I need you alive!"
She was there just that second too late. Because she never thought he'd really go through with it, because – who would be so stupid to jump off a roof? The shock when she saw him fall was so strong that her animal, dark instincts failed her, and when she flicked her hand to stop his fall, it was that blink of an eye too late, and his body hit the ground with a terrible, soft thump.
She feels panic course through her veins – she ist he Dark One, she's the most powerful being in this world – or any world – but she has never felt so powerless, so defeated in her life. I can't lose you, too. But she lost him. She lost. The panic is replaced by anger, a burning ire. The Dark One cannot be thwarted, will not be thwarted. She spreads her fingers and moves her hands over his body, his lifeless, battered body… but deep down, she knows. She knows that this is something not even the Dark One can do. Bring back someone from the dead – that is something that the darkness has never been powerful enough to do. That is something only the light could do, the brightest light and most powerful magic of them all – True Love.
And she does love him, she really does. But she also knows that it's not enough. The Dark One is capable of love, of some kind of love; but the Dark One's love is always selfish and never enough, whereas True Love is always pure, always selfless, means always putting the other person above everything else, above one's own life and darkest desires and urges like greed for power, revenge or whatever force drives the Dark One. The Dark One's love will always be tainted. True Love is the kind of love Killian has always shown her, until his last, dying breath.
Emma presses a hand to her mouth when the realization sinks in that she has let him down. He has entrusted her with his life, and she has let him down. And now it's too late. She throws her head back in despair and lets out a long, pained scream that is not from this world. It's loud, so loud in her head, like the swirling voices and demons that whisper to her, snarl and screech in triumph, knowing that this – this was the last thing necessary to pull her over completely, to abandon all humanness and ability to love that was still left in her, the last thing to make her cross that thin line which there's no coming back from. Welcome to the abyss, Dark One.
The noise in her head makes her sick, and the little voices floating around in the last sane corner of her brain go almost unnoticed, almost. But then she hears them.
I believe in you. You're the Savior. You can do this. I believe in you.
She clenches her fists and wants to yell into the night that she cannot, that they were all fools to believe in her, but it seems like she has lost her voice. It's broken like the lifeless body oft he man lying beside her on the street, the man she loves, dead because of her.
Her head falls down, and her words come out in a toneless whisper. "I can't. It's too late. I can't." She collapses on Killian's chest, covering his broken body with hers, searching something like comfort with him one last time. "Forgive me," she mutters, her hands clenching the front of his leather jacket.
When the first tear escapes the corner of her eye, it's painful, shameful, but after that first one, she can't stop herself and breaks out in uncontrollable sobs. And then it happens. Killian's body starts to ripple under her hands, is shaken once more like a broken toy, lifted from the floor even, and a flash of light, like an explosion, surrounds them for a brief moment before it's gone again. Emma knows the feeling: she has experienced it already once, a long time ago, when she broke the First Curse by kissing Henry, on his deadbed. True Love's Kiss. But she was the Savior then, not the Dark One, like now. It wasn't possible.
She looks down at Killian's pale face while the seconds tick away, her fists clenched, and the silence around her is almost overwhelming, because all the noise in her head – it's gone. She doesn't even dare to contemplate what this could mean, because it really is meaningless, if… carefully, she puts her hand to his cheek. She wants to whisper his name, but she can't.
And then, his eyelids flutter, barely perceptible at fist. She feels her eyes widen so much it's almost painful, and then he opens his. Briefly only, before he squeezes them shut again, his face crunched in pain, but she has seen the spark of life in them. She presses one hand to her mouth, the other one to his chest where she feels his heartbeat again, steady and strong, but he flinches at her touch.
"Bloody hell," he groans, "you do love some good suspense, don't you?"
A shaky laugh breaks through her tears before she throws herself at him, ignoring his pained protest. One day she's going to kill him. But today is not that day.