A/N: Okay, so this is the other oneshot I've promised was coming. This one is NOT a songfic (how surprising is that?). We've seen some of Mark interacting with Zoe and it's really cute big-brother stuff, so I decided to write more. I've seen some stories where he's babysitting her and I thought I'd try my hand at it. But since Mark and Maddy are and forever shall be my OTP, I couldn't just leave poor Maddy sitting on the sidelines while her other half gets a story written, so I'm putting her in too. Please review :D Reviews make me happy!

"Hey!" Maddy greeted Mark at the door of her family's house. He looked her over, noting her disheveled t-shirt and frenzied hair. She offered him a stressed-looking smile.

"Are you okay?" he asked, seeing the state of the living room behind her.

"Yeah," her voice came out in a frantic pant. "My parents just asked me to watch Zoe while they're OTG on assignment. Josh is being of no help, as usual, he's off with…" She was interrupted by a loud yelp as Zoe tumbled out of her bedroom, shrieking with laughter.

"Zoe!" Maddy cried. "I told you to stop doing that!" She gripped her forehead as she looked disapprovingly at her sister.

Mark tried to contain his laughter, but his amusement was given away by his smirk.

"It's not funny, Mark," Maddy grumbled.

"Do you want help?" he asked her, trying to pull together his 'serious face.'

"Much obliged," Maddy said, standing aside to let him in. He entered over the threshold and his eyes nearly bugged out of his head at the state of the house.

"What happened here?" he asked.

"Zoe got bored," Maddy sighed. "So she decided to build a sofa cushion fort."

"Mark!" Zoe ran at the soldier, and she would have bowled him over if he hadn't caught her and swung her up in the air, sending the small child into fits of laughter.

"Hi, Z," he greeted, setting her back down on the floor.

"Do you like my fort?" she asked, proudly standing by the mess of pillows on the ground. Mark glanced at Maddy, who just shook her head tiredly.

"It's great, Z, but..." he knelt down and beckoned her closer, keeping his voice to a stage whisper as if it were a secret, but projecting loud enough for Maddy to hear. "I think you should probably pick up all these cushions before your sister loses it! Besides—I think Commander Taylor would be jealous of how cool your fort looks compared to his."

Zoe giggled as she looked at Maddy. "Okay," she relented, flopping down on the 'roof' of the fort, which promptly gave way and collapsed. Mark ruffled her hair, then stood back up and joined Maddy at her side, a satisfied look on his face.

"How did you do that?" she asked, amazed.

"Children are just one of my many strengths," he said, a smug grin on his face. She smacked his arm playfully.

"I finished," Zoe announced, eager to please her 'big brother.' Mark crossed over to the couch where the fort once stood, hands clasped behind his back, spine rigid like a commander inspecting his troops' bunks. He ran a finger over the fabric and then inspected it for dirt. Zoe eyed him curiously.

"What are you doing?" she asked.

"Inspecting," he said with mock severity in his voice. "You pass," he finally announced, giving her a grin, which she returned.

"Do you want to see my dinosaurs?" Zoe asked excitedly. "I made most of them myself!"

"Sure," he replied enthusiastically, raising an eyebrow at Maddy as the child scampered off to gather her paper Mache creations. Maddy shrugged. Zoe reappeared shortly after, arms full of various species of dinosaurs, all rendered fairly accurately out of scraps of old papers.

"This one's a slasher," she announced, proudly holding up a replica of the fearsome reptile that so often terrified the colony. "And this one's a nykoraptor. And this one," she held up a familiar looking one with leaves dangling from its mouth, "is a brachiosaurus," she spoke the word carefully, as if she was still getting used to pronouncing it.

Mark opened his mouth to speak, but Zoe continued, fishing around in the pile of homemade toys. "And see? I even made little paper Mache versions of Commander Taylor," she held up one with graying hair and an impressive beard. "And of Daddy and Mommy and Josh and me," she held each one up in turn. "And Maddy and you!" She held up the last two, which bore striking resemblance to Maddy in a sundress and him in uniform. Their hands were joined together. "Daddy doesn't like these two very much," Zoe admitted, scrunching up her nose. Maddy groaned and buried her face into her hands as Mark chuckled.

"Here, you take this one," Zoe handed him the slasher model.

"What should I do with it?" Mark asked, accepting the little reptile and squatting down beside her at the coffee table in the living room.

"You have to chase the rover like this," the little girl told him, retrieving a wooden rover that her father made for her from the shelf. She demonstrated what he should do. "Maddy!" she called her sister over. "You take these two," she handed her the two paper Mache versions of herself and Mark, which she hesitantly accepted.

"Now what?" Maddy asked.

"The dinosaurs are coming!" Zoe cued Mark, who did his best impersonation of a slasher's growl before charging the tiny creature at the rover, making Zoe giggle in delight. Even Maddy seemed to be enjoying herself.

Playing with the dinosaurs kept Zoe busy for a long period of time, but she eventually grew bored of the game by the time darkness began setting in. "I'm hungry," she announced.

"Hi Hungry, my name's Mark!" Mark stuck his hand out as if he were shaking Zoe's hand after meeting her for the first time.

She giggled. "My name isn't Hungry, it's Zoe. But I'm telling you I'm hungry!"

"Okay, Zoe-but-I'm-telling-you-I'm-hungry," Mark tried again, giving her a playful grin.

"No! It's just Zoe!"

"Okay, Just Zoe."

The child gave up, turning to Maddy. "Maddy, I'm hungry—what's for dinner?"

"I'm not sure," Maddy relented, deciding not to torture the poor girl any longer. "Mom and Dad weren't supposed to be gone this long but I guess I could whip something up."

"Do it quickly, please," Zoe requested, rubbing her stomach to indicate its emptiness.

"Alright, alright. Why don't you go take a bath in the meantime?"

"Okay," Zoe replied, gathering up the dinosaurs.

"Z," Maddy called the girl's attention back to her, "leave the dinosaurs. They don't need a bath."

Her little sister wilted visibly, but set the toys back down on the table before grabbing her towel and dragging it into the bathroom. Maddy set about gathering ingredients from the refrigerator.

"What'cha making?" Mark asked, leaning over her shoulder to swipe a cut piece of carrot. She smacked his arm away.

"Good stuff," she told him.

He reached for the vegetable again and Maddy allowed him to take one. "What kind of good stuff?"

"Healthy stuff. Vegetables," she elaborated, shooting him a look as he tried his luck in stealing another carrot. "But I can't cook anything if you keep stealing my ingredients!"

Mark threw his hands up in surrender, a grin breaking out. "Far be it from me to prevent you from cooking!"

Maddy returned to prepping ingredients and he seated himself on the barstool, watching intently. "I wish I could cook as good as you," he admitted as she turned the stove on and heated water.

"Watch and learn," she instructed, wielding the spatula like a pointer.

Zoe came out and joined them a short while later, her hair still wet from her bath. She was clad in her pajamas.

"Ready for bed already?" Mark asked, looking her over.

"Not 'til I have dinner!" Zoe told him. "My tummy's rumbling!"

"Well lucky for you it's almost done," Maddy told her, doling out portions onto three plates.

"What about Josh?" Zoe asked.

Maddy made a face. "If Josh wants to abandon the two of us here and go hang out with Skye, then let him figure out his own dinner. Mark," she turned to her boyfriend, "dinner's ready."

He hopped off the barstool and joined the two girls at the kitchen table. "Looks good," he said, "smells good too," he inhaled appreciatively.

"Zoe, eat your carrots," Maddy instructed between bites.

The girl made a face. "But I don't like them," she whined.

"You know, carrots help your eyes," Mark told her, and she looked at him with fascinated eyes.

"Actually, there's no evidence…" Maddy started, but broke off when Mark gave her a knowing glance.

"They do?" Zoe asked, spellbound by the new information.

"Yep," Mark nodded his head. "They help you see better. I love carrots, and I've never had a carno or a slasher or a nyko sneak up on me before. You should eat your carrots or else you might end up with old man eyes like," he lowered his voice, "Commander Taylor!" Zoe's eyes widened and she looked at the orange vegetables with renewed interest, shoveling them into her mouth. Maddy mouthed a silent 'thank you' from across the table.

Mark collected the dishes and began to wash up as Maddy marched Zoe to bed after dinner. She re-emerged ten minutes later.

"She's asleep?" Mark asked, surprised that the little girl was asleep already.

"Out like a light," Maddy confirmed.

Mark shut off the water, drying his hands. "That was fun," he said, back still turned to Maddy.

She caught him off guard when she threw her arms around his midsection, her cheek pressed to his back. "You were amazing," she gushed.

"Aren't I always?" he joked.

"I mean with Zoe," Maddy said. "You're really great with kids."

Mark turned around, putting a hand softly on Maddy's cheek. "I figure it'll be good practice for when we have kids one day…"

She looked at him with one eyebrow raised, a lopsided grin on her face. "We?"

Mark laughed. "Yes, we. We're going to have kids one day, Maddy."

"Who says I want kids?" she teased.

He thought it over a minute. "You do," he decided.

"Why do you say that?"

"It would be a waste of your naturally caring instincts if we didn't have kids," he told her, tucking a loose strand of hair behind her ear. She smiled—the way he said we so nonchalantly was not lost on her. He spoke it like a forgone conclusion, like somehow he just knew they would end up together with a family of their own. He was, of course, right.

A/N: And now we know why they're such great parents to Adelaide and Matthew (go see my Snapshots of Mark and Maddy story if you want some of those future family moments)! They had to start somewhere, and I loved the 'big brother' interaction Mark had with Zoe those few times on the show. Almost all the interaction was between Mark and Maddy, though, so I've been trying to explore his relationship with the rest of the Shannon brood. But I couldn't resist the fluffiness at the end. What did you think? Please leave a review, even if it's only to say 'awwwww.' :)