The relief is overwhelming when his face pops over the balcony, complete with roguish smile and sparkling eyes. She feels weightless as she runs for the stairs, hating every second that keeps him from her, and as they collide and fall and laugh she feels gloriously alive.

This is the moment. Emma promised herself she'd tell him if she got him back, and here he is - more wonderful than she remembered, and somehow all the imperfections of life combine to make him perfect in her eyes. She prepares for it, says she needs to tell him something so she can't back out, and realises he's been waiting for this too.

Emma can see it clearly on his face. For someone who had once been impenetrable, such an effortless liar, Killian has become so easy to read - at least for her. He looks like he knows what she's going to say, or at least thinks he might - and his hope is beautiful. There is insecurity there too, and she knows she could clear it away with a few words.

Those words are right there; she can imagine saying them, imagine the radiance of his smile, imagine the way he'll pull her into a kiss. He won't push her away, she's sure of it.

Almost sure. Love - it's an enormous step, something that changes lives; it's terrifying.

He said she was his happy ending. The thought fills her with as much warmth now as it did when she first heard it, and at every recollection since - but there is also a weight, something like responsibility. What if she's not enough? What if she lets him down? What if he pins all his hope on her, and it turns out she's not worth it?

Emma doesn't doubt him, though. He's worth all the love she has for him.

Believing he was dead - she's rarely known pain like that. She's lost before - terrible losses that still ache, that always will. Graham, Neal, and - far too many times - thinking Henry or her parents were gone from her. She'll never be free of the too-recent agony that was thinking she'd watched Snow die in that rewritten past. And yet seeing Killian die... Feeling the heart-stopping moment her father stabbed him, as instant and powerful and deadly a pain as if she was the one being killed - all the times she'd come close to losing him, she'd never known how it would feel to watch the life leave his face, his eyes lose focus. She'd never known what it would be to see him die and be utterly powerless to stop it, to not even hold him as it happened.

She'd already begun to think she loved him; in that moment she'd known, far too late.

And it was the worst thing she'd ever felt.

Here and now, it was the best. Killian was hers, she was touching him, talking with him, close enough to feel the warmth of his breath, almost hear his heart beating. That time, those hours when he'd been dead, would haunt her nightmares. All her friends had turned to darkness, their happiness lost in the world Isaac and Gold had created, and yet it had been Killian she was fighting for all along. Somewhere in these last few years, even if she'd only admitted it today, she'd come to find that none of it was worth anything if he wasn't there.

He's so beautiful, so hopeful, so expectant, and the words catch in her throat. She loves him, she thinks maybe he loves her back, so why can't she say it? What is there to lose? So much more, surely, if she holds back now?

And yet... it's like she told Regina. If she tells him, it will be real. If she tells him, and then loses him, there will be no consolation, nothing to stem that grief for the rest of her life. If she never speaks it, if no one ever knows, she can pretend she never cared until she nearly starts to believe it herself. Her silence is a shield, a guard against losing him - because he can say he's a survivor all he wants, and she longs to believe it, but deep down even he must know one day their luck is going to run out. He's alive today because Henry and Regina prevented Isaac's story from becoming the only one that's real; if Henry had never picked up that pen, Killian would be lost to her for good.

So she tells him another truth, one that she means but that doesn't mean nearly as much, and he tries to hide it but his face falls and she knows for sure, then, what he was hoping for. She will tell him, she promises herself, but not now, not today, perhaps tomorrow...

There's time.

Until, suddenly, there isn't any more.

She's standing on the edge of a swirling mass of darkness, a tornado clawing at Regina, trying to drive out all the good she's built, to tear away everything she's worked for. And Emma can't let it happen. There was no one to bring Regina back when the darkness first came for her; Emma will have her friends, her parents, her son and her boyfriend on her side. It's not a hard decision really, even when her parents cry out for her, because the darkness needs a vessel and she can't let it take anyone else.

It's not hard until Killian's there, reaching for her, trying to draw her back from the brink. The peace and hope that were there such a short time ago are gone, swallowed up by fear, and he looks like he might cry if she doesn't take his hand and go with him. Emma Swan has never been someone who has looked to anyone to save her, and yet she knows that's something she doesn't even need to ask. He'd jump into that darkness himself if she let him. She understands he's never going to stop fighting for her, and in that moment realises she's known that all along. He will bring her back.

It's somehow the easiest thing in the world to say.

"I love you."

She wishes that she hadn't left it so late, because then the darkness strikes.

Gold had been the Dark one all the time he'd loved Belle. Emma clings to that thought as the darkness swirls round her, claws at her. She can feel it as something more, not just these whirling, twisting ribbons of predatory darkness; it is inside her, too. Something far less corporeal is reaching inside her, tugging at the sheer light she uses for magic, trying to twist it into something horrifying.

A person who becomes the Dark One is still capable of love. That has to be true. Selfish love, though - but was that the Dark One, or Gold?

When it takes you over, would you stay yourself but dark, or become a new person altogether?

If he had known and loved Belle before the darkness, would Rumplestiltskin still have loved her when he was lost to it?

Will the creature Emma is about to become still love Killian?

That's the terror she feels she might drown in, not the cloying power forcing its way into her body. Right now, she knows exactly who she is, and exactly what matters to her: her family. Her mother, her father, her amazing son, perhaps even Regina, and the man Emma is in love with. Could the darkness take that away? Could it make her into someone, or something, who didn't care about them?

The thought that she might not care if they get hurt is terrifying. The idea that she might be the one to hurt them is beyond imagination. She already longs to run to Killian, to prove that he's still real. But now she's the one leaving him, because one way or the other the person that emerges from this is not going to be her.

She trusts them to bring her back. She just hopes they can do it before she does something no one can undo.

A few more seconds, and she can't even see them any more. She closes her eyes against the dark and it's so easy to picture their faces; Snow, David, Regina, Robin, and Killian, standing so close beside her. It might seem like it, but she isn't alone. They'll be with her all the way.

The darkness rises to its peak and, in the seconds before the Dark One claims her, Emma thinks of her family in better times and begs the darkness to let her keep them safe. She thinks of Killian holding her, of his ruffled hair and daft smile as she pushed him down on the bed that evening, and love warms the last spark of light in her heart.

In the next moment, she and the darkness are gone, and the dagger falls to the ground bearing the name Emma Swan.