My brain conjured up this story while on cold medication yesterday. Even though the original was a bit loopier, I decided that I really liked it. This will be multi-chaptered, planned as of right now to contain about three. This is also obviously a future fic, but I'm just going to leave much to your imaginations! Most of this is based on true stories, either of my own or of friends of mine.

Disclaimer: Grey's Anatomy is the property of Shonda Rhimes and ABC. This writing is for entertainment purposes only and is not for profit.

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"Can you tell me again why I agreed to do this?" Mark Sloan asked his wife as they walked up the path to the front door of the Shepherd household. He shoved his hands into his pockets, obviously self-conscious but not wanting to let it show.

Lexie sighed and answered without hesitation, reminding him for the millionth time. "Because Derek is at the hospital, and this is the only night Meredith and I are both free to go out for dinner." She paused, glancing up at him and raising her eyebrows, never losing a step. "And because you love your niece and nephew. And you love me." She smiled sweetly, bumping her arm into his.

Mark remained silent. He couldn't argue with that.

Still, he wasn't completely happy about being roped into babysitting Meredith and Derek's son and daughter for the night. He loved the kids, that fact was for sure, but he was more nervous than anything. He didn't have much experience with children. He knew how they operated and what they generally liked to do, but knowledge was nothing without application. For days, his mind had been replaying a scene in which he lost one of the children or he did something to make them hate him.

Mark and Lexie reached the porch and stood before the large, ornate door. Lexie half-laughed at the tense expression on his face, at the way his blue eyes were wide and mouth pulled taut. "Relax," she said soothingly, gripping his arm. "You'll be fine. I promise. It's only for a few hours. We'll come back from the restaurant and Meredith with take control of her brood again. You'll be fine."

"You're going to owe me big time," he mentioned, only half-kidding, waggling his eyebrows suggestively. Lexie threw her head back and laughed, sleek hair shining in the soft twilight.

"We'll see about that."

Before Mark had a chance to say anything else, Lexie extended one finger and rang the doorbell.

After a few seconds, the door swung open, revealing Meredith. Noise was booming inside of the house. The television was blaring; there were loud, pounding footsteps and the occasional shriek. Meredith, not at all frazzled by the racket, smiled brightly and first swept Lexie then Mark into a hug.

"Hey," she greeted cheerfully, running her fingers through her hair. "Come on in, I just need to grab my purse." Lexie went to take a step across the threshold but tripped slightly on a small pair of cleats and two shin guards. Meredith noticed and sighed audibly. "Damn it, I told him to pick up his soccer stuff about five times, I'm sorry, Lex."

"It's fine," Lexie chuckled, pushing the shoes aside with her foot.

Meredith took a deep breath before hollering in a tone that only a good mother could possess, "Garrett Paul and Kailey Anna! Get your little butts down here and say hello to Aunt Lexie and Uncle Mark!"

Instantly, the two little Shepherds materialized from what seemed like out of nowhere. Garrett Paul Shepherd and Kailey Anna Shepherd stood on either side of Meredith, beaming. Every time Mark saw them, he was blown away at what attractive children they were. Genetics were good to them.

At five years old, Garrett had an unruly mane of curly dark hair, obviously inherited from his father, and eyebrows of an identical color. His skin was lighter than Derek's, the same moon-pale as Meredith's. His eyes were big and blue, completely his father's, with an air of youthful mischief to them. He wore a white cotton karate uniform, and around his waist was a belt of kelly green. There was a gap in his smile, on the bottom row, where he had recently lost his first tooth.

On Meredith's left was Kailey, who was a little girl of three. She was a tiny clone of her mother, right down to the facial structure, thin pink lips, and hair color. The only difference was her eyes, which were the same as her brother and father's. She was inherently slightly shier than Garrett, hanging just a bit closer to Meredith's leg, hugging the small stuffed tiger she took everywhere to her chest. Her hair fell to her shoulder blades, slightly disheveled, and her cheeks were stained with sticky red candy.

The kids saw Mark and Lexie and their eyes became huge with excitement. They squealed and ran to them, Garrett to Lexie and Kailey to Mark. Lexie and Mark laughed, willingly receiving the attempted tackles. After the first round of hugs and kisses, the kids switched adults, and then back again one more time. Meredith watched the four of them with a smile.

"Aunt Lexie! Uncle Mark!" Garrett cried excitedly, waving his arms. "Look what I learned today in karate!" He took a deep, deliberate stance and, eyes focused intently, chopped the air in front him.

Kailey tugged on Lexie's sleeve. "Come and see my room!" she demanded, as she always did when a visitor came, speech still somewhat affected by her young age. Mark and Lexie grinned warmheartedly at each other and the children. They really enjoyed being the favorite aunt and uncle.

In the meantime, Meredith had retrieved her purse from the other room. "No time for that, Kailey, Aunt Lexie and I have to leave for dinner." She stopped for a moment, giving her son a pointed look. "I thought I told you to change your clothes fifteen minutes ago. Go."

Garrett groaned. "But Mom-"

"Now."

Pouting, Garrett left the gathering and stomped up the stairs. He knew when to stand down, even though he didn't like it. He knew what was best for him.

Meredith again seemed unaffected by her victory. After all, it was a daily occurrence. "I'm glad we're going out tonight," she remarked to Lexie, digging through her bag for her cell phone. "You seemed pretty eager to make this date. Besides, I've never been to this restaurant before."

"Neither have I," Lexie replied. "But I hear it's great." Meredith nodded absentmindedly, unzipping her purse's side pocket, still in search of her phone.

"Are you feeling better?" she asked as an afterthought. "Sorry my children got you so sick." Lexie had gotten a nasty case of the flu from the little Shepherds and had been battling it for the past few days.

"So much better," Lexie said with relief, rolling her dark eyes. "I'm so glad that's over." But after there was the smallest hint of a wise smile, something that neither Mark or Meredith noticed.

"Me too," Mark concurred. "Too much holding hair back and vomit for my taste," He smirked jokingly, and Lexie punched him in the arm.

"Hey, at least she's an adult," Meredith commented, raising her eyebrows at Mark. "When Kailey had it, she could never make it to the toilet in enough time. And then Garrett had it right after her, and whenever he would throw up, it would come out both ends." She pursed her lips matter-of-factly, as if poop and puke were the plainest things ever to casually discuss.

Mark grimaced. Some things were just better left unsaid.

Meredith grunted in exasperation. "Where is my phone?" she asked nobody in particular, clawing at the contents of her purse.

Kailey put her little hands on her little hips. "On the couch," she stated proudly, smiling and sticking her chin in the air. Lexie giggled, nudging Mark. He smiled softly.

Meredith raised a single eyebrow at her daughter. "And why exactly is it on the couch?" she asked, placing her own hands on her hips. Mark and Lexie each snorted at the mirror image before them.

"I was playing with it," Kailey answered plainly.

"What does Mommy say about playing with her cell phone?"

"Don't."

"So why did you?"

"I don't know."

Mark and Lexie tried to stifle their laughter at the display as Meredith rolled her eyes and went to fetch her phone. Kailey scrunched her face into a spunky grin, killing the ill feelings with cuteness.

When Meredith came back into the foyer, phone in hand, Garrett came bounding down the stairs in a very mismatched outfit. She stared at him for a moment and then shrugged. She then addressed Mark. "Okay, they'll probably be ready for dinner not long after we leave. Anything in the cabinet is good; they'll eat pretty much anything. Don't worry about giving them their baths." Mark let go a breath of air, realizing that he just caught a break. Baths were one part he was concerned about. "Also, since it's the weekend, don't worry about their bedtime. Just put on a movie and they should fall asleep. We'll be home before my husband, I'm pretty sure. Derek just let me know he got taken into surgery."

"Got it," Mark answered with a nod, hoping he was coming off more confident than he really was.

Meredith gave him a smile of gratitude, touching his arm. "Thanks, Mark," she said sincerely. "I don't know what we'd do without you here. Once the babysitter had other plans and I knew Derek was going to be working, I was stuck."

"It's no problem." The words were almost honest. Meredith turned to her children.

"Okay, Gare and Kay," she addressed them with their nicknames, "Aunt Lexie and I are going to leave now. We'll be back when you guys are asleep. Listen to Uncle Mark and be good, or else."

Mark's heart skipped a beat anxiously. The time was almost there when he would be alone with the little Shepherds. He tried to tell himself he could handle it, twice, but couldn't bring the fact totally into his brain.

"We will," Garrett and Kailey responded to their mother automatically, blue eyes taking on an equal innocent stare. Meredith kissed them each on the forehead, hugging them tightly. Mark watched, marveling at her and how she acted with them. He couldn't fathom how, five years ago, she had instantaneously become a mother the second Garrett popped out. He could remember that day like yesterday, and Kailey's birth as well. Mostly, he remembered how freaked out Derek was for both.

Kailey leaned into her mother's embrace, but Garrett tried to shrink away and wiped his forehead with his palm after Meredith stood. Mark smirked. Typical tough guy attitude.

The kids rushed for Lexie next, hugging her at the knee and waist depending on their height. She cooed their names and a goodbye, bending down to kiss the tops of their heads. Mark smiled tenderly, a warming sensation washing over him. He loved to watch Lexie with the Shepherd kids. It made him think about their possible future children, the intangible glimmers of their future. It made him forget all about his nerves for a moment. But only for a moment.

Meredith and Lexie each shouldered their bags. "Are you good?" she asked Mark, sensing his apprehension and smiling reassuringly.

"As good as I'll ever be," he replied truthfully, shrugging, following up with a nervous laugh.

"You know how to reach us," Meredith continued. "If you can't get either of us, Derek will have his phone on at the hospital." Mark nodded, seriously hoping it wouldn't come to that. "Okay, let's head out."

Lexie kissed her husband gently, a soft smile on her lips. "Good luck," she whispered, squeezing his hand, looking dreamily into his eyes.

"Bye, guys. I love you!" Meredith blew each child one final kiss before she and Lexie stepped outside. The door clicked shut behind them almost menacingly. It made the hair on the back of Mark's neck stand up. This was it. He was alone with the wolves. They were officially his responsibility for the next few hours, however long Meredith and Lexie would be out.

For a moment they stood there, two pair of shiny sea-blue eyes staring into his. Mark lost track of time, he couldn't tell if they had been frozen there for a second or a minute. He tried to reassure himself. He knew the Shepherd children; he had since they were born. They knew him too, and they liked him a lot. He could handle them for a little while by himself. How hard could it possibly be?

For another instant, Mark and the Shepherds were in a deadlock. Then, Kailey's big blues moved once again to the closed door. They widened, and her face suddenly contorted. The stuffed tiger fell to the floor as her fist went limp.

Mark cringed and froze. He knew what was coming next.

Kailey sucked in a lungful of air before she let out a loud, piercing wail, tears beginning to stream down her porcelain cheeks.

It was going to be a long night.