Domestic Destiel; Dean and Castiel have a five-year-old called Mary who they saved three years ago. Sorry for how bad this is, I just had some head-canon and needed to get it out. So here it is:

"Daddy?"

Dean nodded, not looking down from the morning paper, humming in acknowledgement; "yeah baby?"

"What's that?"

"What's what?"

"On your arm!"

"There's nothing on my arm, baby."

"No daddy, look! There!"

Dean felt a tiny little finger poke him in the shoulder; he sighed quietly, putting down his paper and looked down at his daughter, who was gently poking his shoulder where Cas' brand was. His lips thinned; the mark had been there so long he'd forgotten about it. Much like his anti-possession tattoo, it was just a part of him, like his freckles.

"Oh, um... That's papa's hand."

The little girl giggled; "why?"

Dean smiled and reached out, gripping his daughter by the waist and hauling her on to his knee; "well Mary... You know what papa is, right?"

"An angel!"

"And... Do you remember how we met?"

Mary giggled as Dean began bouncing her on his knee; "he saved you from Hell."

"Exactly. And when he did, this happened," Dean explained, motioning to his shoulder.

"What does it mean?"

"It means I love your daddy very much," Cas answered, appearing behind Dean and plucking their daughter from his knee. Dean smiled and turned to watch his angel-husband cradle the five-year-old to his chest, whispering things in her ear that made her giggle. His heart melted when he saw them together. Castiel had become almost human, whilst still maintaining his angelic powers, and little Mary was the cutest thing on the face of the planet. She'd been rescued when she was two when her parents were possessed; there'd been no way to save them, and Mary had no other family to take her in.
He became fiercely protective of her, refusing to leave her in an orphanage or another home, insisting he and Cas could look after her fine. And to Sam's surprise they had. Dean stopped hunting - or at least stopped going on the dangerous hunts - and stayed home with Cas and Mary; home being Bobby's. Dean even got an honest job, saving up money to get his new family their own home.

"Why's my hand not on daddy? I love him too!"

Dean smiled at Mary's pout.

"Ah, but do you love him more than me?" Cas challenged, giving his daughter an assertive stare. Mary comically put her finger to her lips and looked up at the ceiling, before nodding.

"Yes!"

Dean chuckled and pulled himself up, wrapping his arms around Castiel and Mary; "come on, don't fight over me. You both love me equally. Right?"

Cas frowned playfully; "I suppose."

Mary crossed her arms across her chest; "no! I love you more than papa! Lots more!"

She began bouncing in Cas' arms, making grabby hands at Dean until he pulled her to him.

"Ok, you love me more... But papa still gets his hand on my shoulder."

Mary pouted again; "but I want to have my hand on your shoulder too!"

"We'll see."

He pressed several kisses to her face, making her giggle and squirm until he plopped her back down to the floor. Still giggling, she ran out of the kitchen to go play in the living room. Dean smiled happily at Cas, sliding his arms around his waist.

"Jealous?"

Castiel huffed out a breathy laugh, resting his head on Dean's shoulder; "she's picked up the Winchester-stubbornness."

"That's a yes, then?"

Smiling, Cas looked up at his husband, giving him an I-love-you-so-much-I-can't-even-begin-to-explain-look; "I don't know who's worse."

"You love it."

"I love you."

Dean's heart melted, again; "I love you too."

Dean was lounging across the sofa, absentmindedly flicking through TV channels whilst Mary did finger-painting on the floor. There were week old newspapers laid out underneath her to prevent paint from getting on the carpet, something Dean wasn't too bothered about but for some reason Castiel was some kind of clean-freak. Mary giggled as she painted cats, dogs, lions, and other four-legged creatures which all looked the same with her under-developed skills. Dean smiled, loving the sound of his daughter enjoying herself.
It was a warm day; Cas was outside doing something to the garden, leaving Dean to watch their daughter paint wearing his ratty jeans and wife-beater. The heat was slowly getting to Dean; he began to feel drowsy; Mary's giggles were beginning to lull him to sleep. He awoke from his semi-consciousness to a wet feeling on his arm and Mary giggling down his ear.

"Look daddy! I love you much more than papa!"

Dean looked down and smiled at the bright blue tiny hand-print on his arm, the cool paint warming up with his skin. Mary had a huge grin on her face and a blue hand.

"So you do."

Letting out another giggle, Mary did a small victory dance and fell down to her knees to continue painting. Dean looked down at the paintings she'd done, picking one up.

"I think I'll put this one on the fridge, yeah?"

Mary nodded, not looking up from her art; Dean got up from the sofa, walking through the kitchen - depositing the painting on the counter - and went out through to the garden, smiling at his husband kneeling by a flower-bed. He quietly walked up behind him, reaching out to grasp his shoulders.

"Hello, Dean."

"Hey Cas... You're losing by the way."

"Hmm?"

"Check it out."

Castiel looked up, frowning at the blue hand-print on Dean's arm; "oh dear."

"Yeah, how are you planning on retaliating?"

Cas wiped his hands clean on his gardening jeans and pulled himself to his feet, sliding his arms around his husband's waist; "if she's playing dirty I might have to up my game."

Dean laughed, pressing a soft kiss to Cas' forehead; "I actually like it. Y'know?"

"What, the rivalry between our daughter and I, or...?"

"The hand-print... Maybe if it was a little higher up, though."

Castiel nodded, getting a good look at the hand-print; "a little clearer too?"

"...Do you think I should?"

"It's certainly a nice idea."

Dean smiled, pulling Cas a little closer, rubbing their noses together; "you won't be jealous?"

"Don't be silly."

"Good."

Tightening his grip on Cas, Dean pulled his husband in to a soft kiss, smoothing out the fabric of his shirt where it had creased at the small of his back. Cas hummed appreciatively, raising his hands to grip on to Dean's shoulders as the kiss transitioned from PG to R.

Castiel smiled at his daughter bouncing around the front room. Dean was due home "when the big hand was on the three", which it was. Mary had been sat staring at the clock intently until quarter past, when she jumped up singing "daddy's nearly home!" repeatedly. Cas had accidentally - and foolishly - told her Dean had a surprise for her. There was the familiar rumble of the Impala's engine outside, making Mary squeal in delight and run to the window.

"He's here! Daddy's here! Look!"

Cas smiled and wrapped his arms around her waist, pulling her up to sit against his hip. She vibrated excitedly, waiting for Dean to enter the house. When he did, Mary scrambled in Cas' grip, trying to rush to her other father.

"What's my surprise? Papa said you have a surprise for me! What is it?"

Dean chuckled and ruffled her blonde hair; "hold on a sec, baby, daddy needs to talk to papa, ok? Go wait on the sofa."

Mary nodded and obediently went back in to the living room. Dean gripped Cas' arm and pulled him in to the kitchen; his first job being to re-stick Mary's finger-painting back on to the fridge. Castiel smiled.

"So?"

Dean shrugged his jacket off, hissing in pain a little, and shrugged off his overshirt, before rolling up his t-shirt sleeve. There was a square of black plastic taped to his right shoulder. Cas smiled.

"Looks like you could use some mojo."

Dean laughed and nodded, peeling the black plastic off. Castiel gently placed his hand on the shoulder, relieving Dean of any pain.

"So... Let's go surprise Mary!"

Dean pulled his sleeve back down and led the way in to the living room where Mary was sat on the sofa, her tiny legs dangling down, her hands neatly folded in her lap. Dean grinned.

"Hey, Mary."

The little girl grinned up at her parents; "daddy!"

"You want your surprise?"

Mary hopped from the sofa, bouncing about the floor until she landed with a thud at Dean's feet; "what is it? Is it a doggy? What is it?"

Cas chuckled and picked Mary up so she was head-height with her father. Still grinning, Dean rolled up his sleeve, revealing a tattoo of Mary's hand-print, similar to Cas' brand. Mary squealed loudly, wriggling about to get a better look.

"It's my hand!"

"Are you sure? You might have to check!"

Giggling, Mary put her hand over the tattoo; a perfect fit; "it is! It's my hand! Look, papa! My hand is on daddy too!"

Castiel smiled; "so you do... I suppose that means you love him more?"

Mary pouted; "no. We love him the same. Uncle Sam said I need to share him."

Dean grinned and plucked his daughter from Cas' arms; "that's my girl. But just so you know, I love papa more than you do."

The little girl looked absolutely scandelised; "you do not! I love him more!"

Castiel smiled, wrapping his arms around his odd but amazing little family.