A/N: We just don't know. It was one of those things that came up suddenly and demanded to be written. Title is taken from Darwin's work on the subject. Unimpeachable fluff. Although, because it's me, slight hints of angst. More family-oriented than shippy by leaps and bounds.

Takes place in the not-so-distant future.


She's never had much experience with babies.

Don has. Don has brothers and sisters and cousins and parents who still live in New Jersey and the whole clan has already come and gone, like a pack of well-meaning wolves, circling her newborn Kenzie, discerning features (as if Kenzie has anything more but an undecided smudge of a nose, or the same blue eyes all infants have, as if she and Don both don't have dark hair) and foretelling greatness or some mother's curse, passing her daughter to and fro until plopping her back into the bassinet, telling Sloan to sleep having once ascertained her daughter's place in the power structure at just past 2AM in the hour following her birth.

Her own half-siblings are distant, with decades and her father's first ex-wife in between them. Sloan grew up observing them like they were some closely-related species, sorted in the same genus as her but definitely no further related than evolutionary cousins. She can tell you their behavioral patterns and linguistic trends, but very little beyond that. Her own mother, her father's much younger second wife, was killed in a drunk driving accident when she was four, and so Sloan thought, it was the end of her line.

(Her father, in his mid-forties by the time of her birth, definitely thought Sloan to be endangered.)

Her daughter is born three weeks early to the day.

Which Sloan figures to be typical—her daughter, setting the curve, even in her first foray into life. She studies little Kenzie (MacKenzie Sabbith Keefer, 6lbs 7oz, nineteen inches long, all perfectly respectable for a little girl born from an entirely brilliant woman and named after another) as the sun rises onto gleaming windows and Don promises to return within the hour, kissing them both before slipping out to tend some minor catastrophe at Right Now before fully intending on taking the rest of the week off.

She sighs, trying to gauge the passage of time by Kenzie's little breaths, the minute contractions of the muscles in her cheeks, the promises fluttering through her own brain.

(The kind that are impossible to keep, like I'll always be there for you and I will keep you safe.)

"I'm your mother," she says in response to the impossible promises, almost sounding sure of herself. "I don't really know what I'm doing, Kenzie, but I'm your mother. There are worse circumstances to be born into, I promise, even if I'm not sure I'll be good at this yet. But I think we both have a lot to learn, so let's just promise to forgive each other our mistakes now."

(Not quite so endangered as her father had assumed. Strange as it seemed, she and Don did fit together extraordinarily well, and someone loves her father's strange, awkward offspring who had once been a five-year-old with pigtails standing on her tippy-toes watching her father's engineering friends play poker.)

Running a finger down the slope of Kenzie's nose, Sloan decides that Don's mother was incorrect. She likes Don's nose, but her child is not all Keefer. Almost holding her breath, she shuffles her daughter in her arms, before tugging back the hat on her head and brushing a kiss atop her downy hair, smiling down at her.

Her father will call later, Sloan's sure. And her half-sister will take the time off to help him fly out to New York, so he can meet his youngest granddaughter. Until then, she'll make due with her pack of very enthusiastic Keefers, she thinks, until there's a knock at her door in the Mount Sinai maternity ward.

"Come in," she hazards, unsure of who would be here this early, just at the start of visiting hours, smiling widely when Will steps through the door with a (rather tame by his standards, probably to Mac's credit, Sloan thinks) bouquet of spring blooms. "What are you doing up this early?"

Will just rolls his eyes, setting the flowers down onto the bedside table and leaning over to kiss her on the cheek. "Hi Mom."

"Crazy, right?" she answers, not quite able to keep her eyes off the bundle in her arms for more than a few seconds. "Kenzie, this is your Uncle Will. He's wealthy and childless, so start sucking up now."

He laughs. "You're already named after my wife, so you won't have to try too hard." He looks surprised when she offers Kenzie for him to take. Not a bad kind of surprised; his face softens when he gathers the swaddled infant into his arms, sitting down in one of the two chairs next to the bed. "Mac went in with Don to try to fix the control room meltdown, otherwise she'd be here. She's pretty pissed I get to meet you before she does."

Will clearly has experience with babies, adjusting his hold on her daughter easily, but unlike when Don's mother and sister took Kenzie from her arms earlier—very early, ridiculously early, she will have to have a stern talk about timing to Kenzie—this morning, it doesn't make her feel inadequate that most of her knowledge in this world is focused on economics and how to anchor a news show.

It just makes her happy, to see him smiling down at her daughter. Even if it's kind of crazy, seeing big, tall, Will McAvoy holding her teeny-tiny baby. Crazy in the good way, of course. He's like her big brother.

"She's beautiful, Sloan," he murmurs after a long minute, reaching for her hand. And then his smile slides into a smirk. "Now I have two MacKenzies to spoil."

"An abundance of MacKenzies," a second voice says jovially from the doorway.

Sloan feels her grin prickling at the corners of her mouth. "Morning Charlie."

"Don called." After closing the door behind him, he crosses the room with open arms before settling onto the side of the bed opposite Will, wrapping her in an embrace and kissing the crown of her head. "Although I should have figured Will would beat me here." She leans into him. "Now, of course your MacKenzie is very pretty, but has anyone told you yet today that you look very beautiful, Mom?"

Mom. She's someone's mom. That's still so absurd. She and Don have a tiny little family.

She laughs. "Will neglected to tell me that, so no."

"William," Charlie admonishes.

Which doesn't bother him in the slightest. "Shh… I was distracted by my niece."

"Well, share," Sloan says imperiously, as Charlie rounds the bed to sit in the chair next to Will's. "Kenzie, your Grandpa Charlie."

Charlie doesn't have a choice. He's Grandpa Charlie, just like its Uncle Will and Auntie Mac, as easily as she's Mom and Don's Dad. Her daughter deserves nothing but the best, so she'll give her the best. rnd Regardless of the fact that she's ambushed him into being one of Kenzie's innumerable relations (besides, with her own father in California but for all but maybe two weeks a year, it makes sense for Kenzie to have a Grandpa from her maternal side in New York. It's only fair, really, she shouldn't be deprived of these things at such a young age) Charlie looks delighted, expertly taking the baby from Will and holding her like an old pro. Sloan almost laughs, looking at two middle-aged men making silly faces at the sleeping newborn.

"Don's family spent three hours debating who she looks like," she offers after a few minutes of watching them look at Kenzie. "I still can't decide."

"That's not important," Charlie answers.

Will nods in agreement. "We know she's very beautiful, just like her mother, so that's all that matters."

"Everyone knows the real question is if your little girl will grow up to be on-air talent or a producer," Charlie adds, trailing a finger down the baby's cheek. "She's got a 50/50 shot."

She frowns, pursing her lips into half a smile. She'd forgotten; her daughter is half Keefer, but one hundred percent broadcast journalist, a species unto itself. "Is there any empirical evidence for either of those traits being heritable?"

"Not a single shred," Will answers happily.

"She'll be a producer, of course," Mac says, breezing into the room at Don's heels. "She'll be in the Control Room with Daddy and I while Mum and Uncle Will are on set. It's all about influence." "Now let me see my namesake."

"That was quick," Will says, looking up at his wife.

Mac sighs, leaning down to kiss Sloan's cheek. And after discerning there are only two seats in the room, and both are occupied, perches on her husband's lap to look down at Kenzie in Charlie's arms. "It looked like an intern just shoved their hand into the motherboard and ripped out a handful of wires. Shame Don had to get a phone call for that."

Don, to his credit, shrugs it off.

"Ah, the family was here with them. I'm too happy this morning to get upset over it." Don takes up the spot next to her that Charlie had previously occupied, lacing their fingers together. "How are you feeling?"

Sore and exhausted, but definitely more at ease than she had been an hour and a half ago. She turns her face up to her husband, tugging him down for a quick kiss. "I'm fine."

"She looks radiant," Mac says, eyes crinkling, even though her gaze is otherwise occupied by little MacKenzie. "And this little one is absolutely precious."

Sloan studies the scene around her.

It's like sixth grade life science, she thinks—kingdom, phylum, class, order, family, genus, species. Life has its own taxonomy; finding where you belong in the order of things. You have the family you're born with, and then you go out and find your kind. Sloan's found hers, she realizes, watching Mac and Will debate on-air talent or producer, feeling Don laughing next to her. Charlie looking on fondly.

It's life in a nutshell.

Everyone sorts in somewhere. Everyone finds their species eventually. Everyone finds their pack to run with.

But, she promises her daughter silently, that the family she's has been born into won't be so bad either.


Thanks for reading!