A/N: Nate-Silver-Black on tumblr put out a post about best friends turning into lovers when both chance thought there was no chance of it happening. Dear God has there ever been ANYTHING more in my wheel house? ANYTHING? I nearly fleshed this out into it's own fic, but I still have a good four or five going on so I didn't. Hope you enjoy.

A/N 2: I have a four or five fics going and I promised myself this year I'd get that number down to 2 or 3 (I don't count the Chuckquinn ones because who knows when that maniac is going to stroll into town) This one could be very long and huge. But it would be no spying, no Intersect, just a freaking angsty love story that we all know where it would go. That's why I didn't….after a good hour of talking myself out of it. If you guys REALLY want it, it would be a bit. I've got two with my eye on how to finish….you know even my beta laughed at the one shot idea….

Disclaimer: I don't own Chuck.

"Happy Birthday, Chuck."

That's what she said, as she presented him with his "cake." Since they met almost 20 years ago, on each birthday, she gave him a cupcake with a single candle placed in the middle.

"What do you wish for?" she asked. "For us to not to have made that promise?" There was amusement on her face, but something else was there… sorrow? Sadness?

"I'm sure of all the 'arranged' marriages in the world, being married to your best friend isn't the worst," he replied. She shoved his shoulder the way she always did, and gave him his smile. In the 20 years he had known her, no one else ever got that smile; only him.

}o{

They were eight when they first met. Sarah had moved in next door with her mother Emma, and Sarah was furious. She wanted to go with her dad. But the courts had found Jack unfit, especially after he changed her name from Jenny Burton to Sarah Walker. She refused to change it back to Jenny… at eight… that was Sarah. Stubborn, but fiercely loyal.

That's how the play wedding had come about. The one that was still on video tape from when they were eight, and had been converted to DVD. Chuck and Sarah both had a copy and watched it often, the other never knowing…

They were best friends. They had been inseparable. The night Emma was rushed to the hospital and Sarah stayed over… she slept in Chuck's bed with him, two friends holding each other. As they got older, they would nap together, in a platonic cuddle.

When Jimmy Reed had broken Sarah's heart, dumping her when she was 14, and she worried she would never be married because guys were awful, he promised her if she wasn't married by 28, he'd marry her.

She would sneak into his bedroom at night through the 'Sarah window', as everyone called it, when she needed to talk. Whether it was about her dad being in jail, her fight with her mom, or just why all her girlfriends were just bitches.

She had made him practice kissing on her, until she deemed him a good enough kisser to go to the high school prom. When that night had ended in disaster, she had held him as he cried, the two of them sitting on the beach watching the waves.

They had gone to the same college, and nothing had changed. The night after she first had sex, she called him. They walked the campus for hours, neither saying a word; just the others' company was enough. Each wishing the other had been their first, but never admitting it, for fear of ruining their friendship.

Their senior year in college found them at a party together, both wondering why no one else wanted to go out with them. Bryce told them that everyone assumed they were in a long-term relationship. That night, the two got drunk, and ended up back at Chuck's dorm room. He and Sarah griped about everyone, and both said maybe they should just be together. They began to drunkenly make out, and who knows what would have happened if Chuck's roommate hadn't stumbled in. They spent the night together, but nothing happened… other than each wondering why they weren't together.

The next day they both apologized to the other, and they each swore to help the other find someone. They graduated, found jobs, and went apartment hunting. It just so happened Echo Park had two open units, and there they both lived. When they were single, Friday nights were movie night, Saturday nights were dance night, and Sunday was dinner. Neither wanted to admit to the other that most nights they went on dates with others were during the week, because they couldn't bear not having the weekend to see each other.

After a bad day, conversations by the water fountain were the norm. They normally shopped for groceries together, but if they didn't, and one saw something the other wanted, they immediately texted or called to see if they should pick it up.

When filling out paperwork, Chuck always asked her his blood type, social security number, or any of the other various things that he should know.

It took her breakup with Bryce to finally push him over the edge. After Chuck spent the night consoling her after the breakup, and she spent the night snuggled against him in his bed, Chuck searched for and found Bryce.

"Why in the hell would you cheat on her, Bryce?" Chuck asked, stopping himself from shoving Bryce, but just barely.

"Because she was never faithful to me," Bryce replied.

"Bullshit, she never cheated on you. She never had sex with any other dude!"

"Chuck, it wasn't sexual fidelity… she loves someone else, man," Bryce explained, shaking his head. "But you can't see it, or won't believe it."

"What are you talking about?"

"Dude, she's in love with you."

That had been two months ago, and Chuck hadn't dated since. He watched her when they were together; how she was tactile with him, how others would look at them and think they were a couple. Could it be true? Could she really feel for him the way he did for her?

}o{

"Cheer up, it's not binding," Chuck joked. She twisted her lips and gave her head a shake. "I get it, being married to me must sound awful," he teased.

"No, it wouldn't be," she said softly. "I'd be married to my best friend." The silence enveloped them, and for once in this situation, he wasn't worried. He wasn't nervous. "Now, what can I do for you for your birthday?"

"Normal parameters?" Chuck asked.

"Normal parameters," she said with a grin.

"Go out with me," he said softly.

"Sure, where," she chirped.

"No, Sarah," he said, locking eyes with her. "For one night, just one… go out with me."

"Chuck," she began.

"I love you," he blurted out.

She grinned and placed a hand on his chest. "And I love you-"

"No," he said covering her hand with his. "I love you." She was silent. "I know you are way out of my league-"

"I will kick your ass if you ever say that again," she nearly growled.

"Noted, but I know we've never broached this subject." He swallowed.

"What if we ruin what we have?" Sarah asked.

"How?" Chuck asked her. "If you don't feel that way about me, just say so, and I will drop it right now. Right. Now." She didn't say anything, and he took a step toward her. "I have an idea."

"I'm listening," she replied.

"Let's try something we've tried in the past, except we're not teenagers anymore, and we're not drunk."

"You want to kiss me and see if there's something?" she asked. Chuck nodded, and then waited patiently. "Kiss me, Chuck." The way she said it, she sounded a little out of breath.

He kissed her gently, but within a second that was out the window. She grabbed hold of his shirt and pulled him in. He ran his tongue against hers, and thought if a bomb went off, he wouldn't care.

She pulled away for a second, searching his eyes. "Why the hell did we wait so long?" she asked, and dove back in. She began to pull him toward the bed, and he stopped her.

"What?" she asked, a mischievous grin on her face. "Am I too much for you?"

"Always," he replied, a grin on his face. "But I asked for a date."

"You want a date?" Sarah asked and glanced at the bed.

"Yeah," he said. "Sarah, I'm greedy. I want it all with you."

"I'm a mess, Chuck, you know that," she replied.

"I know, and yet I love you."

"You keep saying that I'm going to hold you to your offer," she said smiling.

"I really do want the date," Chuck replied. She sat up, ran her hand down the side of his face.

"I was talking about what you have to do now that your 28," she said, bouncing her eyebrows at him.

}o{

"Okay, this is weird," Sarah said, sitting across from him at the Mexican restaurant.

"What, being out with me?" Chuck asked.

"No, not that, it's just… you know how you go on the first date with someone, and all that… stuff that happens?"

"Yeah, we're so past that."

Sarah grinned at him. "Are you sure you want to do this?"

"Do you not?" he asked, worry clouding his face. "I mean, if you don't want to go one step further, then it's back to us being how we were."

"Chuck," she said softly. "You love me. You can't go back from that." The teasing lilt in her voice just made him grin.

"You know, I'm wondering if you didn't tell me you love me at the apartment. Really love me," he teased back.

"You wish," she said, rolling her eyes at him.

"Yeah, I do," he admitted. She froze. "God, Sarah… I mean what are we both looking for? Someone we trust, that cares about us, that is there for the other in the worst times?" Tears were in her eyes, but she nodded. "We've done all the hard stuff, the only thing we're missing, is the fun stuff."

"But what if… what if it doesn't work out?"

"But what if it does?" Chuck asked. He looked around, and leaned forward. "And don't forget… I know all your kinky little wants." She swatted him on the shoulder good naturedly and made a face at him. "All we have to do is remember that when something goes wrong, we talk to our best friend."

"This sounds really easy," Sarah said.

"Did you just call me easy?" Chuck asked. Sarah giggled. "I mean I'm not saying I'm not…" She began to laugh out loud. "It's your call."

She wiped her eyes, tears having formed from laughing so hard. "Okay," she said, and with a short nod, she scooted around the booth until she was sitting beside him. She lifted his arm and put it around her shoulders, snuggling against him. "Doesn't feel any different." Chuck curled his finger, tucked it under her chin, gently lifted her face, and kissed her lips, sweetly. "Okay, that was different," she admitted, after he pulled away.

"Different bad?"

"No, Baby. Different perfect."

}o{

She opened the door to his apartment like she always did. She'd had a key from the first day he moved in, and he had one for hers. She turned toward him as he shut the door, shoving him against it. "Happy birthday, Chuck," she said sultrily, as she pushed him against the door, kissing him as if it was her job.

"Second best birthday ever!" Chuck exclaimed as she moved away. She began to shake as she laughed, giving him an amused look.

"Chuck, that was some random dude in a Darth Vader outfit," Sarah said, putting her hands on her hips. "You're telling me that is better than this?"

"I mean, adult Chuck says no, this is better… 11 year-old Chuck…" he pressed his lips together and widened his eyes, making her laugh. She took his hand, and led him to the bedroom. "Hey, what are you doing?"

"I think maybe it's time we leave 11 year-old Chuck out here, and adult Chuck and Sarah have some adult time," Sarah replied. He stopped walking, still holding her hand, and she danced back to him.

"I think a lot has happened between us today, and I think that we should consider slowing down and just letting this… rest. Is that the right word?"

"I mean if we're doing it right, we're cooking with gas," Sarah said, raising her hand, and Chuck giving her five. "Fine, but I'm staying here, because that's what we do, and I'm cuddling."

"Okay," Chuck replied.

"I might get handsy," Sarah admitted.

Chuck leaned in and rested his forehead against hers. "I hate to break it too you, but you've always been handsy."

"You liked it."

"Yeah, I did, and I do." She looked into his eyes and neither saw the fear that they expected to be there. "I'm sorry."

"For what?"

"For taking so long to trust you with my biggest secret," Chuck said softly. "For not believing in us. For not telling you I love you all those times I realized it."

"I thought you said you wanted this to rest?"

"Can't resist me, can you?" Chuck asked. She backed away and held up one finger. She walked over to his bookshelf and pulled out a worn-out comic. It was the one she gave him for the first birthday she had known him. She handed it to him, a grin on her face. Chuck opened it, and a card fell out. He bent down to get it, saw it was her handwriting, and opened it.

Chuck,

For your birthday I'm going to give you something, I'm giving you the truth. I love you. Not just as my best friend, but I love you. I can't bring myself to tell you to your face because I'm scared. What if you don't feel the same way about me? What if you don't want to try because it could ruin what we have? I left this here because I know today, like every year, you'll pull this comic out and read it. It's your call, Buddy. Whatever you decide, I love you.

Sarah

Chuck looked up at her, tears in his eyes. "You know I don't really like Care Bears, right?"

"Chuck, for God's sake, I was eight, it was a comic book. How many times do I have to apologize?" They both smiled at the running joke, now on its 20th year. "Come on, let's go to bed."

}o{

"Did you two have your normal pre-birthday night celebration?" Ellie asked Chuck and Sarah.

"It was a little different this year," Sarah said. "Ellie, how do you make this better every year?"

"Bartowski secret, you'd have to be one. Sorry, Sarah," Ellie said.

Sarah turned to Chuck. "I'm calling in the marker," Sarah said, making everyone laugh, knowing their marriage deal as teenagers.

"So, let me get this straight," Chuck began. "Finding out Ellie's secret receipt is what it takes to get you to marry me?" Ellie stopped, stunned. This wasn't normal. Chuck nodded. "Sounds fair." Sarah turned back to Ellie, innocence all over her face.

"Is that good enough, or do we need to go elope?" Sarah asked.

"Wait," Ellie began, as Chuck and Sarah began laughing. Ellie mocked glared at both of them. "I hate you both."

"Ellie, we've only been dating a day, I think marriage is a bit much," Sarah said, grinning at her. Ellie's eyes went wide.

"So, wait a week?" Chuck asked.

"Two," Sarah replied. "Holding out for better offers." Chuck began to laugh, but Sarah turned to him, serious. "I'm sorry, there would be no better offers, no matter who asked." Chuck smiled at her, and she gave him his smile.

"Oh my God," Ellie said softly. Sarah reached in her pants pocket, handing Chuck a pair of ear plugs, and another to Devon. "Oh my God," she said a little louder. All three stuck their earplugs in.

}o{

"Wow," Sarah said, catching her breath and snuggling against him. "I mean, I have laughed during sex, but always because what happened was so bad."

"I'll take that as a compliment?"

"Chuck, my best friend loves me, and is amazing in bed," she said looking up into his eyes. She took his hand that was wrapped around hers, playing with the fingers. "Is this real?"

He kissed the top of her head, making parts of her flutter. "Yeah, it's really real."

"We're really doing this."

"Uh, we done did it," Chuck said, getting a light smack from her. "But yeah, we're doing it, and gonna keep doing it the rest of our lives." She sat up and turned, looking at him. "What?" he asked. "Where else is this going to go?"

She studied him a minute, then shrugged. "Fine, but can we wait a few weeks before we tell Ellie? My ears still hurt." With that she snuggled back against him. "I love you, Chuck. Happy birthday."

"Best one ever," he said softly, kissing the top of her head.

A/N: Boy I could have made that a bunch of chapters but…too many out there. DC