A/N: So this little Chuck/Blair fic was oddly inspired by the "Sandcastles in the Sand" episode of How I Met Your Mother. And although Chuck may seem a little OOC, I have discovered that I enjoy writing fics where he shows a romantic side. Because, let's face it...we all know there's one hiding in there somewhere. But anyway, I hope you enjoy. And as always, feedback is always appreciated. Thanks!

Disclaimer: Don't own Gossip Girl. Obviously.

Blair Waldorf stood outside on the balcony of her penthouse, her silky, designer gown flowing around her in the cool night wind. There were hundreds of people inside, all there to celebrate her eighteenth birthday, but the one person she wanted to see was nowhere to be found and she needed a moment to collect herself.

"Happy Birthday, Waldorf," a deep voice from behind her caused her to turn around and when she saw who it was, she dropped the champagne glass she was holding in surprise.

Ignoring the broken glass, she walked over to the simple, brown, unwrapped box he was holding out to her. "This doesn't look like a box from Tiffany's, Bass," she said in a critical voice, trying to mask the fact that she was ecstatically happy to see him.

Chuck smiled at her smoothly. "Why don't you stop judging me and open it? You may just find that you'll be pleasantly surprised," he said confidently.

Blair opened the box and pulled out a snowglobe, but instead of snow, it was sand surrounding a sandcastle. "Sand," she said, shocked, staring at the gift.

"Sand?" she repeated, this time in an incredulous voice, looking up at Chuck, her brown eyes shooting daggers.

She shoved the globe back to him. "It's my eighteenth birthday and you got me sand?!" she exclaimed, throwing her hands on her hips angrily. "Did you get dropped a few too many times on your head when you where a baby? Is that it? Because it's either that or you're on some kind of drugs but either way you must be completely brain damaged. It's the only explanation for giving me sand."

"I guess this means you're not big on presents with simply sentimental value."

Blair raised one of her perfectly arched eyebrows and stared at him as if her were nuts. "What the hell are you talking about, Bass?" she asked, very confused.

"Read the inscription," he said, holding the globe back out to her.

"What?" she asked.

"You heard me," he said, gesturing at her with the gift. "Read. The. Inscription," he reiterated as if he were talking to a small child.

Sighing, Blair took it back. "'I'll keep that promise. 8-23-95,'" she read. "I don't get it," she said, placing the globe on a small table beside then.

Chuck took her by the hand and pulled her close to him. "'Promise me. Promise me that when we're married, we'll live in a sandcastle just like this one,'" he recited, whispering in her ear.

Blair recoiled away from him. "Have you completely lost your mind?" she asked, throwing her arms in the air in frustration. "A:," she said, holding up one finger. "I would never want to live anywhere withyou let alone marry you and B:," she said, throwing up a second, "you can't live in a sandcastle. They get washed away by waves," she said like it should have been obvious to him.

"Come on, Waldorf," Chuck said, still smirking despite the verbal bashing he was receiving. "You can't possibly be telling me that you don't remember."

Blair had had enough. "You know, this is getting real old, real fast. If you don't tell me exactly what this whole little spiel of yours is about, so help me God I will chop off-"

"Slow down, would you?" Chuck said, holding up his hand to keep Blair from finishing that last unpleasant thought. "There's no need to get huffy."

He took Blair by the hand and led her over to an antique, iron bench Blair's father had picked up in Italy. "But let me take you back about 13 years,' he said, sitting down and pulling her with him. "The Hamptons. Our parents sipping Martinis in the clubhouse while you and I played on the beach…building sandcastles…" he said, trailing off, trying to prompt her memory.

And it worked. Blair's eyes suddenly grew wide as Chuck's words triggered a reaction in her brain. "Oh, my God," she said, turning to him in realization.

Chuck gave her one of his infamous smirks. "It's all coming back to you now, isn't it?" he asked.

Blair turned from him and sank back into the bench, as all the memories from the one day in August came rushing back to her.

"WHACK!" That was the sound of five year old Blair Waldorf hitting five year old Chuck Bass in the shoulder with a plastic shovel.

"Hey, what did you do that for?" Chuck demanded, looking up at Blair from the sandcastle he was building through squinted eyes as he tried to block out the sun that was reflecting in her metallic silver swimsuit.

Blair placed her little hand on her hips and jutted it out, the classic "angry female" pose. "You're doing it wrong," she informed him.

Chuck turned back to his sandcastle, tuning over a bucket to add another wing to his creation. "It's not rocket science. It's a sandcastle. There's not a wrong way."

"It's lopsided."

"Fine," Chuck said, dropping the bucket as he stood up and brushed himself off. "You do it," he told her as he walked away.

Blair, realizing her mistake, took off after him. "No! Chuckles, wait!" she said, reaching him and sopping him by taking his hand. "I can't do it. I'll get sand on my hands."

"What did you call me?" Chuck asked, looking at her in confusion.

"Chuckles," Blair answered, giggling. "It's your new nickname. I thought of it all by myself."

"Promise me you'll never call me that again and I'll keep building," he said, staring into her eyes to let her know he was dead serious.

Blair bit her lip, internally battling with herself on whether or not she was willing to accept those stakes.

Chuck, seeing her hesitation, made a move to continue walking.

Blair sighed in defeated. "Okay, you win. I promise."

"That's better," he said, satisfied, as the two of them journeyed back to the castle. Chuck settled back down into the sand and continued building as Blair stood by and kept a critical eye on his work.

An hour or so later, once it was finished, Chuck and Blair stood back with their arms crossed as they checked out the finished product. "You know, it's actually not bad," Blair said thoughtfully.

Chuck rolled his eyes. "Gee, thanks," he said. Even at age five, Chuck Bass still had a solid sense of sarcasm.

Blair elbowed in him the side. "I'm not kidding," she said seriously. "It even glitters in the sun. Like gold," she added as an afterthought. Even at age five, Blair Waldorf had a solid taste for expensive things.

"It's pretty," Blair said, turning away from the sandcastle to look at Chuck.

Chuck took her hand. "You're pretty," he told her as seriously as a five year old could.

This took her by surprise. "Really?" she asked, giggling and taking a newfound interest in wiggling her toes in the sand as a deep blush rose in her cheeks.

"Yeah. And I'm gonna marry you someday."

She looked back up at him, her eyes sparkling with excitement. "Promise me," she said softly, pulling him into a hug. "Promise me that when we're married, we'll live in a sandcastle just like this one."

Blair pulled away and looked at him, scrunching up her nose. "Except you know…bigger," she said, giggling.

"I promise," Chuck said.

And then they sealed their deal with a pinkie swear.

Blair tuned back to Chuck with tears brimming in her eyes. "I can't believe you remembered," she said softly, looking at him in a new light.

Chuck smiled and reached up to her and brushed a stray hair that had gotten loose back behind her ear. "I can't believe you didn't."

"We were inseparable then. What happened to us, Chuck?" Blair asked, a few tears beginning to escape.

He shrugged. "That fall we started the first grade. You met Serena and things changed. It was as if you didn't need me anymore. You left me behind."

She could feel her heart breaking as she remembered how nasty she had been to him over the years. "I'm sorry," she said sadly.

"Nah," Chuck said, shrugging her apology off. "Doesn't matter."

Blair took his hand in hers. "No, I'm serious. You were so sweet."

"Were?" he said with a laugh, raising an eyebrow.

"Yes, were," she said teasingly. "But you're kind of making up for all the in between years now," she said, now running her hand up and down his arm.

Chuck smirked. "Does that mean you'll forgive me for giving you sand for your birthday?" he asked, his eyes dancing.

"As long as you promise to build me that sandcastle."

"I promise."

And they sealed their deal with a kiss.