Cas starts to get nervous when he sees his daughter fly above the kitchen window.
He drops the wrapping paper he'd been using for Sam's present and heads for the backyard, not exactly sure what he's expecting to find there.
"Dean," he says hesitantly, "uh, what are you doing?"
Dean tosses Cassidy up into the air once more and catches her under her arms when she comes back down, dissolving into a fit of giggles.
"Our babygirl's a superhero!" Dean says, spinning around as fast as he can as Cassidy shrieks and laughs. "Kicking the ass of anything that gets in her way! Here, show Daddy."
"I told you about swearing in front of her," Cas mutters, glaring at Dean.
"She'll hear it eventually," Dean says, sliding his hands under Cassidy's stomach as she stretches out both arms, her hands curled into fists. He carries her forward until she reaches out and hits Cas on the arm.
"POW!" Dean yells, pulling Cassidy back and shaking himself a little, for extra emphasis. Cas wants to scowl, especially when he feels his lips quirk up into a smile instead.
"POW!" Cassidy repeats. "Pow, pow, pow!"
"That's my girl!" Dean grins as he places Cassidy gently down on the grass. Once her father's hands leave her body, Cassidy's off and running around the yard, scaring off squirrels and the wayward bird sitting on the fence. Dean walks over to Cas and wraps an arm around his waist. "She's like our very own Carol Danvers," Dean says proudly.
Cas looks at him warily. "Carol who?"
Dean takes an exaggerated step back and stares at him. "Carol Danvers. Captain Marvel?" Cas' face remains blank. "Have I taught you nothing?" Dean wails.
Cas ignores his husband's tantrum and rests his head on Dean's shoulder. "She's just like you, you know," he says, watching Cassidy continue her romp around the yard.
"What?" Dean asks. "I mean, yeah, she's got my ridiculously good looks and radiant charm," he flashes Cas a brilliant smile, "but she's all you, man. I mean, hell, her nickname's friggin' Cas." Dean plants a kiss on Cas' temple. "Plus, those baby blues aren't mine, y'know."
"She's brave," Cas says softly, leaning further into Dean's shoulder. "Like you."
Dean looks at Cas and turns his body to face him. "Don't give me that shit," he says. "Brave like both of us."
"Dad! Daddy!"
Dean and Cas look up to see Cassidy standing proudly on top of the shed. Her sneakered toes are hanging over the edge of the shed's roof, and she's got her hands in fists on her hips.
"Jesus fucking-Cassidy, freeze!" Dean yells as he and Cas scramble forward. Cas gets there first and holds his arms out to their daughter. She hops forward and lands in them snugly, giggling at Cas' panicked expression.
"I flew!" she cries, gazing up excitedly. "Didja see, Daddy? I flew! And Dad didn't even have to help me!"
"No more flying, baby," Cas says, setting Cassidy down on the grass. "Not until you're older."
"Cassidy Mary, how did you get up there?" Dean says, staring hard at the six-foot high shed that their two-foot-tall daughter somehow managed to scale.
"Slide." Cassidy points to the swingset right next to the shed, and sure enough, the platform behind the slide provides an all-too-convenient bridge for the overly adventurous Winchester girl to get onto the shed's roof.
Dean and Cas look at the swingset; Dean cocks his head like a bewildered puppy.
"Huh," they both say together.
"I want you to move that," Cas tells Dean.
Dean opens his mouth to answer but before he can say anything, a shrill buzzer rings, echoing through the screen door and into the yard. "Brownies!" Dean yelps, and runs inside.
"You are a child," Cas says, watching as Dean dons oven mitts and gingerly pulls the brownies out of the oven.
"Says the 800-year-old angel who still licks the batter off the spoon." Dean looks up at him and smirks. He sets the tray on the stovetop to cool for a few minutes and heaves himself up onto the kitchen counter. It's not the most comfortable sitting surface, but he knows how much Cas hates it, so he sits there whenever he can. He grins widely when Cas glares at him.
"Tell me that's supposed to be Sammy's present," Dean says, pointing at the kitchen table, which is cluttered with wrapping paper, tape, ribbons, and a shopping bag.
"It will be, but I got distracted by seeing our daughter get tossed up in the air and fearing for her life."
Dean smirks and motions for Cas to come closer. Cas begrudgingly does, his back to Dean, and Dean wraps his arms around Cas' shoulders. "'M not gonna let either of my Cas-es get hurt," he mumbles, planting a kiss on top of Cas' head. "Y'know that."
Cas smiles and looks down at Dean's hands resting on his chest, runs his hand up and down Dean's forearm absentmindedly.
"But c'mon," Dean says suddenly, jumping off the counter. "We're gonna be late for Sammy's...thing. So turn that," he motions to the table, "into less of a shitshow, and I'll turn these," a nod toward his brownies, "into further perfection, and we'll go."
"I hate you."
Dean smirks before pressing his lips against Cas'. "Love you, too."
As far as Winchester parties go, Sam's is relatively uneventful. There was none of Dean drinking too much and accidentally wandering into the neighbors' yard and puking in their pool (after having to be the one to apologize profusely for his husband's…colorful vocabulary as well as vomit, Cas made sure that event didn't repeat itself); Sam didn't light his shirtsleeve on fire trying to get the grill going; Cassidy didn't get another concussion after getting bucked off Sam's dog, Harley, when she tried to ride him around the yard. They got to meet Sam's new girlfriend, Sarah, for the first time, and they resembled something like what Cas would picture being a relatively normal family.
Dean had let Cas use the shower first, so as Cas climbs into bed, he gets to be serenaded by his husband's muffled rendition of "Heat of the Moment." He rolls over and is about to switch off the light when he notices a thin paperback book sitting in front of the alarm clock on the nightstand. Cas grabs it and scans the cover—Captain Marvel: In Pursuit of Flight. Right next to the title is a small sticky note with Dean's handwriting scrawled across it.
"Read up, sweetheart."