This Underworld reunion headcanon has been plaguing me for weeks and I finally had a chance to put it to words. This is based on various spoilers (A&E saying that 5B will be reminiscent of S1, the CS filming spoiler in the rain, etc…).
After the first few days, he stopped trying to leave. Each step leading him right back in, facing the same walls, entering the same empty rooms, grew heavier with the weight of hopeless eternity. This warped version of the home he'd chosen, once a bright possibility had become his prison. The door opened to a familiar view, white picket fence, short clipped grass the color of her eyes, but it's all an illusion. Some dark magic, or oncoming insanity (probably both) has him trapped, the outside turning in each time he's attempted to cross the threshold.
It's at the end of the first week that he notices the pattern. The rising moon, ever changing in life, is frozen in death. Curved into a crescent, the shadows have yet to shift, the stars, the clouds, each night the same as if time has yet to pass. But the sun always ascends, shielded from view by the gloomiest of clouds, waking the same birds, at the same time, on the same tree. The world here, under, it's his worst nightmare. An endless loop spent in what was to be their home, alone, forever.
Three weeks in, he stops looking out the window. He's lost all belief in ever seeing anyone again. No one has passed by on the street, not at dawn, or midday, dusk or any time in between. The telescope is there, but like everything else, with blackened lenses, is only there to taunt. It matters little, as the ever present fog makes it impossible to see more than a few feet past his fence. Their fence. No, it's only his now. It was never theirs anyway. It was his idea, and then hers, now his.
He stops counting days. The bed upstairs becomes his sanctuary, spending days under the covers in and out of sleep, hoping to find her somewhere in his dreams. When he wakes up warm, he knows she's been there, even if he can't remember. His eyes crack open to bone chilling cold more often than not, the black quilt he's burrowed beneath like ice and his muscles painfully cramped. Its torture, but he takes what he can get, never knowing when the warmth will finally be gone, only that one day it will.
This morning he's warm, so blissfully heated he fights to stay under, refusing to open his eyes. He's sure he's won the battle when he hears the birds, their morning song something new, too alive to be real. Lost in his dream, his eyes open to the bright rays of the sun, impossibly peeking through the crack in the curtains. Reaching out, he flinches at the heat beneath his fingertips, the dark fabric of his quilt having soaked up the heat of the incoming light. Unused muscles strain as he moves to stand, joints cracking as he crosses to the window to draw back the curtains to view the world his subconscious has created.
Heavy droplets are falling on the grass, that rare magical mix of sun and rain, where it feels like everything is possible. The fog has lifted and he can see for miles, even swears he can spies movement in the distance, a passing car, smoke in a neighboring chimney. Curiosity leads him down the stairs and to the front door, wondering if his dream world will finally let him leave. Closing his eyes, he turns the knob and pulls the heavy door open and stands there just for a moment, listening to the blissful sound of the raindrops hitting the porch. It's as beautiful as anything he's ever heard, until…
"Killian!"
The red of her jacket is the first thing he sees, the vibrant color almost painful to his eyes after too long in his shadows. But then he sees her face, her tears evident even with rain plastering her hair to her cheeks, her lips trembling in wait of a response.
No sound comes when he tries to speak, his throat dry and clenching, the sight of her even in his dreams a blessing and a torture. Swallowing hard, he tries again.
"Emma?"
The sound of her name from his lips has her running towards him and he towards her, the fact that he's able to leave the house barely registering as her arms come around him and he's crushing her with the strength of his embrace. He knows this is just a dream, that she isn't actually here, but she feels…she feels so real. Leaning back, he threads his fingers through her wet hair and guides her mouth to his and nearly cries at the first touch of her lips. Rain is soaking them to the skin, but he's like a man possessed, desperate to keep kissing her, afraid she might disappear. She starts to pull back and he can't help it, he grips her tighter, tries to kiss her harder.
"Killian…"
"No, please…don't go, not yet…"
His fingers tangle further in her hair as he stumbles forward, but her hands at his back fist into his shirt and she gives a forceful tug. His forward momentum halted, she brings one of her hands to his face and pushes his rain soaked hair from his eyes.
"I'm not going anywhere, Killian. We came to take you back home."
He begins to shake his head to refute her, but then he feels it, the hum of her magic pulsing against his cheek. The raindrops glitter in the space between them as they catch the light from her palm, and in that instant, he knows this isn't a dream. Reaching up to cover her hand with his, he leans forward to rest his forehead gently against hers.
"Emma…how?"
"I'll tell you everything once we get back to the group. Let's get inside and dry off, and find your hook…and your shoes."
Looking down, he can barely see his socks through the grass and mud, and for the first time in what feels like forever, he laughs. Emma looks at him with a confused smile, but soon joins him, laughing along with him as they run hand in hand back towards the house. As they reach the threshold he stops, the reality of stepping back inside again ending the happy moment almost as soon as it began.
"What is it?"
"Before you got here, I couldn't leave this house. Each time I tried, I'd end up right back in the hallway like some bloody labyrinth with no way out."
Her fingers tighten around his and she steps inside in front of him, urging him to follow with a gentle nod of her head.
"You got out today. Things are changing, Killian…"
"Because of you, Emma."
"Maybe…I don't know?"
It's the tinge of insecurity in her voice that leads him forward, his basic instinct to always support her stronger than his fear. His feet leave mud tracks on the hardwood as he steps inside to face her, his free arm pulling her close so he can press a kiss to her temple.
"I believe in you, love."
She relaxes against him and they just hold one another for a long moment, their wet clothes dripping in puddles at their feet. Finally feeling like himself once again, he can't help the next words that seem to fall from his lips all of their own accord.
"If I'm wrong, Swan, we'll just be stuck in this house together forever, with a very large bed."