Playing fast and loose with the lore, but I had good intensions.

Dean and Anna have been married for five years.

He still can't quite believe it.

They met at a church picnic Jess and Sam dragged him to, Anna had come up to him in her blue summer dress, all pale skin and pretty red hair, sitting on the hood of the impala and looking down at him through the windscreen.

"What are you doing in there?"

Dean had waved his beer, leg hanging out of the open door. Anna had looked down at him a few seconds longer.

"Can I have one?"

"I suppose you could." Because for some reason he felt like being a jerk, but then Dean's permanent setting was 'kind of a jerk' in those days. The girl frowned as if trying to work out an intricate problem.

"May I have one?"

Dean handed her the beer.

A six pack later they were parked in an out of the way gravel lot, classic rock mumbling through the speakers, the skirt of the pretty blue dress hiked up as far as Dean could get it.

Afterwards, in an unaccustomed moment of intimacy, Dean laid, pressed against her back, stroking her abdomen. Anna smiled slightly, her voice husky and quiet. "I'd hoped it would be like that."

They dated, Dean discovered Anna couldn't cook worth a damn but loved to paint, not stupid little pictures but enormous canvases of abstract winged things and slashes of red and black. She watched football with him even though she didn't like it, loved baseball for all its rules and statistics, drank whisky like a pro and read so many battered old books Dean could never keep track.

Somewhere along the line, in between discovering all these things, he'd fallen in love with her.

For all her social gracelessness and shyness, Dean learnt quickly that she was insanely good at sex. In a kind of, surprised and a little enamoured with every single aspect of the whole messy, awesome process. Their honeymoon involved two pairs of handcuffs, a hell of a lot of lube and some other stuff Dean would never be able to tell Sam about even if it was totally awesome.

Anna couldn't have children, and accepted the news with a quiet nod and a shrug, like it was more than she should have ever asked for.

"What are you thinking about?" he'd ask in his more reflective moments.

"If the stars are dying before we even see them...are there any left?" Anna would mutter, or else wonder aloud if she'd left the water running downstairs, or whether Sam was allergic to all nuts or just peanuts. Anna was always honest, whatever the question.

They were laying the table for dinner with Sam and Jess when Dean tossed Anna the gift he'd gotten her, a cake slicing knife with an ornate handle. She caught the black box and opened it, catching the handle of the blade as it tumbled free of the velvet casing.

The air filled with the smell of burning skin, Anna yelped and dropped the blade, hunching over her palm and moaning in pain.

"Anna?" Dean darted forwards and made to hold her palm, Anna held it away from him and shook her head.

"It's fine, it's fine I'll just go run it under the faucet." She hurried into the kitchen and he heard the water running. Dean looked down at the knife, then gingerly picked it up. Nothing happened. He turned it over and looked at the hallmarks on its surface.

Following Anna into the kitchen he reached out and tentatively brushed the handle of the blade at her red hair, instantly it singed and strands fell to the floor. Anna jumped and shook with pain, as if she could feel the burning of her hair like her own flesh.

"Dean...please don't."

"Why is it...why does that hurt you?" He knows he's witnessing something weird, something bad. The silver scorching her pale skin, her perfect hair.

"Because it's silver." She turns to him and her blue eyes, usually so clear and beautiful, are darker than a clouded sky. "I'm not..."

"What are you?" he breathes and he isn't quite sure how he knows, why after such a small thing he is so sure that his wife, his amazing wife, is some kind of 'thing' and not a human being. But he is.

"Please..." her voice is low and calm, but cracking with distress. "Please don't make me do this." Her fingers, light and gentle, reach out to touch his arm and to Dean they feel the same as they always have, ever since the day he handed her a beer, just because she'd asked. "I'm so happy...I've been so happy with you." She soothes quietly. "I've made you happy...so please don't make me leave."

"Anna..." he sets the knife down, but something in his stance must show he isn't going to let this go because Anna closes her eyes and shakes her head. "Anna...you can tell me, I love you." She opens her eyes and even though Dean's said it a hundred times over the last five years, it's like she's hearing it for the first time all over again. "Whatever secret you've been keeping...it doesn't change that."

"It will." She swallows. "and I'm sorry, because I don't think I should have lied...but I didn't think..." She blinks and a tear makes its way down her face. "I just wanted you so much and I thought...I thought if you didn't want me, couldn't want me...maybe there was a way to get you to change your mind."

There's a leaden weight in his stomach.

"What did you do?" She doesn't answer. "Anna...if you did something to me you have to tell me what it was..."

"Not to you." She look appalled. "I'd never...I didn't do anything to you."

"So what..?"

"I'll show you." She sighs, almost crumpling in on herself, and then leads him through the house, up into their bedroom and to the closet. At the back, under old shoes and fallen shirts, she finds a locked tin box, which she brings to the bed and opens with a key from the bottom of her jewellery box. Inside are a few photographs, an old brown leather wallet and a birth certificate. She hands the items over mutely.

The photos show Anna, only much younger and sitting side by side with a boy of her own age, pale skinned and blue eyed with a shock of black hair.

In the pictures Anna's eyes are green. Dean can see that clear as anything.

The birth certificate is for Castiel Novak, with a notation about his twin sister, Anna. The wallet contains his picture, as an adult, and Dean recognises his eyes this time – blue and bright and piercing.

"My sister, Anna?" Anna says quietly from her place beside him. "is in a mental institution." She breathes out sharply. "I...I'm what's called a 'shifter' I can change into, anyone, as long as they're still alive, as long as I've touched them at least once. That's why silver burns me."

"Who are you?" Dean can barely pull the words together, because either his wife is crazy or...the silver, he can't forget the silver, the burn.

"My name is Castiel Novak...we've never actually met face to face." She swallows. "but I...I used to watch you and, I thought you were...but you'd never look at me because I was a man and..." she looks at Dean, eyes wide and anxious. "It was monstrous I know that but...but she was just sitting there with everything I needed, and it was only going to be once." She shakes her head. "only once, just so I could have you, once. And then...and then you wanted to see me again." Another tear drops from her eye. "and again and I kept thinking that I'd tell you...and then you asked me..." a harsh sob of a breath escapes her. "you asked me to marry you."

"Change back."

"No...no Dean you don't want to see..."

"Change back, just...if it's true...just stop looking like that. Please."

Anna gets off the bed and slips her dress off over her head, Dean looks away. He hears the dress hit the floor, followed by the soft sounds of underwear falling to the floor. What he hears next is an awful, fleshy, ripping sound, a shuddering gasp and a moan of pain. He can't not look as Anna peels her skin away, as her teeth drop from their sockets, as the soft shells of her ears slough off and her nails are shed from her hands.

He wants to scream but he can't make a sound.

After what feels like a long, long time, an eternity of horror, there is just a wiry, naked man, streaked with blood and sweat.

"Dean." Even though his voice is impossibly deep, scratching at his throat, it carries the same love, the same warmth as Anna's voice.

"It's been you this whole time." Dean needs to say it out loud, because memories are pouring in on him. Anna lying in his lap, laughing. Anna sleeping beside him, writhing underneath him, pottering in the garden, handing him a cup of coffee, cocking her head to one side when she doesn't understand something.

All of it was a lie.

"Yes it was me." Anna...Castiel – takes a blanket from the bed and wraps it around his waist. "Dean, please..."

"Get out...just...get the fuck out of here." The other man flinches.

"I can't...I..." he crosses his arms over himself and seems to shrink, looking so small and fragile. "I don't have anywhere else to go Dean...I don't want to leave you."

"You're a fucking monster." Dean spits. "You..." he can't fathom all the levels on which he has been wronged. "You've been wearing someone else's...face...for five years."

"I know I..."

"Sleeping with me, talking to me...getting me to fall in love with you and the whole time you were lying. You were impersonating your sister." Dean feels his heart crumple up like a beer can shot fathoms beneath the sea. It fucking hurts. "You're a liar."

"I love you." Castiel looks at him hard, blue eyes identical to the ones that smiled at him from across the bed that morning and asked him what he wanted for breakfast. "That wasn't a lie...I love you and everything...everything that I told you about me was true." He shudders, suppressing a wave of violent emotion. "I've been with you for five years...please don't do this to me now." He looks down at the pile of gelatinous waste skin and hair. "I know I'm a monster...I know what I've done is disgusting but I can't take losing you...not after everything." He looks up at him through tear spiked lashes. "You can't tell me you can just stop loving me...you might want to but you can't."

Dean looks at him and he can't say it. He can see Anna, his wife, in every curve of this man's body and in the lilt of his voice, the movements of his limbs and face. A long pale hand reaches towards his own covering it, warm and soft.

"Dean..." the fingers stroke over the back of his hand, turning it and tracing his palm. There's no seduction in the gesture, just the other man seeking the comfort of a touch once so familiar, now suddenly denied.

"You..." Dean grits his teeth. "Don't you ever, change into anyone else again...will you promise me that?"

"Anything." Castiel says quietly. "Please...just, let me stay?"

"Everyone is going to think..."

"I don't care." Castiel's hand rubs up his arm, to his shoulder. "Whatever you want to say, that's fine...whatever story you want to tell."

"This doesn't mean that we're..." Dean shakes his head to clear it. "we can't just keep going like we were before."

"I know." Castiel nods in agreement. "however you wish to proceed. I'm just..." he sighs. "I'm just... I'm lucky, if you let me stay I'll be grateful."

Dean recognises the desire in him for what it is, and pulls Castiel into an embrace, holding him close and realising as the other man's body relaxes, that he still smells the same as he did that morning.

"How did we meet?" Dean asks, gruffly, into Castiel's hair.

"You know how..."

"Just tell me."

"I found you at the church's picnic. You were in your car drinking a beer, so I asked you if I could have one...and you said that I probably could...you were laughing at me...so I asked if I might have one...and you gave it to me."

Dean knows then that he could ask Castiel another question, ten, twenty, a thousand questions about their life together, and he would answer every single one accurately and honestly.

"Ok..." Dean sighs. "Ok...let's just...let's take some time with this."

Castiel nods emphatically. "Thank you...for giving me a chance."

"Thank you...for telling me." Dean says slowly. "for not just...I don't know...running away."

Castiel smiles genuinely, and it's like Anna's smile, the sun coming out suddenly. At the same time it's new, and Dean feels a jolt of pleasure at having coaxed it out.

"I'd never leave you."

"I'll never ask you to...again." Dean stumbles over it, but it's ok.

They've been married for five years.

And Castiel can read between the lines.