Context for anyone who hasn't read the Gravesen Chronicles: in this AU, Scott is the son of Bob Lang, who later married Hope van Dyne and had Cassie, making Scott and Cassie half siblings with a large age difference instead of father and daughter. In Gravesen Chronicles canon, Scott died of neuroblastoma at age 5, long before Cassie was born. Also, Happy New Year!

What If...Scott Lived to Meet His Half Sister?

Scott waved goodbye to his friend and grabbed his suitcase from the trunk. The car was mere yards from the driveway when he heard the door open and excited footsteps rush outside. "Scotty's here!" a young voice called, and within seconds the small figure flung herself at him, nearly toppling him over.

He put the suitcase down so he could hug her back. "Hey Cassie."

She looked him dead in the eyes and said, "Don't ever go away to college again."

Scott chuckled. "No promises."

"I'll hide all your stuff so you can't leave."

"I think Mom and Dad might have something to say about that, but you can try." And he knew she would.

Picking up his suitcase, he followed Cassie back to the house. Dad and Hope awaited them, both eager for hugs. Scott had only been gone for two and a half months, and he'd FaceTimed them plenty of times, but evidently they still missed him like crazy. Cassie didn't appreciate his attention being taken away from her, and began tugging at the hem of his T-shirt before he'd even released Hope.

"How's your semester?" Dad asked.

"Busy, but great. I joined magic club."

"Did you learn any tricks?" Cassie asked.

"Yep. I'll show you later."

"Okay!"

"Why don't you go drop your things upstairs and then we can catch up?"

"Sure."

Cassie tailed him all the way up the stairs. Scott didn't expect he'd get a lot of alone time over this break, based on what he'd seen of his little sister so far. She plopped down on his bed while he opened his suitcase to pull out a few essentials. He was only here for five days, so he decided to leave most of it where it was. Scott opened his closet to discover that Cassie (or more likely, Hope) had taken to using it as extra storage space for toys.

Cassie, legs swinging freely back and forth, asked, "Did you have sex at college?"

Scott ground to a halt. What did his eight-year-old sister just ask him? More importantly, how did she know what that meant?

"Did you?" she reiterated.

"Cassie, what are you talking about?"

"I don't know what it means, but I know sex is a thing people do in college. I heard Mom tell you on the phone not to do it without protection. Is it dangerous?"

"That's…not something you need to worry about, Cassie," he told her. "It's a thing only grown-ups do."

"Like alcohol? Did you drink alcohol in college?"

"No. I'm not grown-up enough yet." Cassie would not be the first to know that Scott underage drank at a party ever other weekend for the past two months. And she would never know that he hooked up with a girl in his physics class at one of those.

She crossed her arms with a huff. "You're boring."

"If I'm so boring, why are you still in here talking to me?"

"You're less boring than Mom and Dad."

"Oh, I see."

He headed back downstairs to the living room, Cassie trailing him like a loyal dog. Hope had already laid a collection of his favorite snacks out on the kitchen table. Scott's eyes lit up. After months of college food, he looked forward to eating the things he'd grown up with having a dietician for a stepmom. It would be a difficult adjustment to go back. Scott grabbed a handful of cashews and answered the endless series of questions his parents peppered him with. Despite their regular conversations, there was still so much they wanted to know. By the time they ran out of things to grill him about, he'd depleted the entire bowl of cashews.

They went for a walk around the neighborhood after that, Cassie hopscotching across the sidewalk tiles. Scott watched her with a smile on his face. He'd missed that youthful enthusiasm while he was away. College students were only enthused by free food and canceled classes. Being around his sister reminded him there were more things in life worth getting excited about. They ran into a few of their neighbors, all of them eager to see Scott home.

Scott was born in San Francisco, but he didn't remember any of it. Dad moved them out here to the New York area barely two months after he was born, one month after his mom left without any sign of where she was going. Hope came into the picture when Scott was seven, Cassie when he was ten. Unlike many kids, he didn't resist the introduction of a new parental figure to his life. He'd gone so long without a mom, and Dad never hesitated to tell him the truth about her departure, so he was just happy to finally have someone fulfill that role. It also helped that Hope was an amazing parent.

He'd been even more excited for Cassie to join their family. Most of his friends at school had siblings, but he'd never had anyone to play with over holiday breaks or make fun of his parents with. Then Cassie came along, and he finally got to be a brother. It was his favorite job in the world. Hence why he didn't feel the least bit of shame playing hopscotch on the sidewalks with her.

Dad made his favorite dinner—tacos—and Hope scolded him for letting most of the filling fall onto his plate before he even managed to take a bite of it. She always said that Cassie was a cleaner eater than him even as an infant, and honestly she wasn't wrong. Scott had more than a few food stains on his sheets on his bed at school that he had no intention of ever letting her see.

After dinner, per Scott's request, they broke out the Clue board. It had been a favorite game of his ever since he was old enough to understand the rules. Cassie had finally reached an age where she didn't have to play on a team with someone, and she immediately claimed Miss Scarlet as her playing piece. Hope took Mrs. White, Dad chose Colonel Mustard, and Scott got Mrs. Peacock. He always chose Mrs. Peacock. As a kid, he liked it because her name was also a cool animal, but now he appreciated the irony of playing as an old lady character.

He was somehow dealt all weapons as his rumor cards. Not a single character or room in his entire deck. It would make identifying the weapon easier, but it was more difficult to start rumors in many different rooms as opposed to with many different weapons. Hopefully he'd roll good numbers. Last time they played, right before he left for school, Cassie still hadn't learned to flip her paper over when she wasn't writing on it. Now, she kept it hidden. Scott was glad he didn't have to resist the urge to cheat off of her anymore. It reminded him of how she used to play Old Maid: always picking the card on the far left side.

Much to his delight, Cassie still hadn't grown out of playing with the weapons pieces between her turns. She spent a decent portion of the game stabbing him with the knife. In return, he awarded her a trophy for Best Stabber. Even Dad jumped in on the fun and pretended the dumbbell piece was impossibly heavy.

"It's not heavy Dad!" Cassie insisted, lifting it easily.

"It is, you're just super strong," he countered.

"You're ridiculous."

"You bet, kiddo."

Cassie rolled an eleven and marched right into the pool at the center of the board to correctly guess the circumstances of the murder. It was Scarlet in the kitchen with the knife. Which was funny, because they were playing in the kitchen and Cassie stabbed Scott with the knife piece many times. Once the game concluded, it was her bedtime.

"But I want to stay down here with Scott," she whined.

"Scott's a big boy, his bedtime is later than yours."

Scott bit his lip thinking about the time he usually went to bed at school. His parents would flip out if they knew about the number of near all-nighters he'd pulled, sustaining himself through the next day with Monster drinks and willpower alone.

With a huff, Cassie relented to bedtime and trudged upstairs to change into her pajamas and brush her teeth. Dad tucked her in and the three of them stayed in the kitchen for another hour and a half before deciding to turn in themselves. Scott knew he wouldn't fall asleep anytime soon with his sleep schedule being what it was, but he didn't want them to also know that. He brushed his teeth and changed into pajamas and decided to just play games on his computer until his eyelids grew heavy.

Scott guessed he fell asleep around one thirty or two in the morning, with the hope of sleeping in until at least ten or eleven. Instead, he was woken at eight o'clock sharp by something bouncing repeatedly on the bed. "Wake up Scotty, so we can play!" Cassie called. Scott reached under his head and threw his pillow at her. She collapsed to the bed in a fit of giggles, then threw the pillow back.

"I'm sleeping," he told her.

"No you're not! You don't sleep talk."

"Well I want to be sleeping."

"But you have to wake up! There's so much to do."

"Yeah. Like sleep."

"Don't be boring."

"Sleep's not boring. I have cool dreams."

"Like what?"

"Before you woke me up, I was dreaming about sleeping in."

She stood back up and plopped down hard enough to shake the whole bed. "Sleeping in is for the weak."

"My calc professor would agree with you," he grumbled.

"Come on, Scotty. I've been waiting ages for you to come home and now that you're here I don't want to miss a moment."

Scott pulled the blanket up over his face so she couldn't see his wide grin. Man, he was so lucky to have a family like this, to be able to enjoy this along with rowdy college life. He curled up in preparation and blanket-bombed Cassie, wrapping her up in a tight cocoon. She squealed in delight and surprise. Scott struggled to maintain his grip as she wiggled to escape, and they ended up toppling off the bed to the floor in a tangled heap of blanket.

Probably having heard the thump, Hope knocked twice and asked, "Everything okay in there?"

Scott and Cassie burst out laughing.