Their first date starts in disaster.

Derek is running late. As they're heading out the door for their reservation, Casey's heel breaks off. They manage to make it to the restaurant in time—thank goodness for a fifteen-minute grace period. As they're being seated, a grease fire breaks out in the kitchen, and the restaurant is evacuated.

The restaurant is, arguably, probably having more of a disaster this evening. Still, their date has not started out well.

They sit in the car, spending more than a few minutes debating where they should go. They've thrown around plenty of ideas—everything likely to be packed by the time they get there, and they're starving at this point—when Casey sighs. "Let's just go home."

His hands tighten on the steering wheel. As long as he's known her, Casey has been the type to read into things; Derek blames all the books she enjoys. It creates unrealistic expectations for life and romance, and he thinks that she's likely to see the start to their evening as a sign, as a bad omen that this wasn't meant to be. The whole thing—them together again—would be over before it had even started. Serenity was gone on a sleepover, and he wasn't sure when they would have another opportunity like this.

Despite his reservations, Derek says, "Okay." If Casey has already written them off, he needs time to think of something that might convince her.

Casey pulls out her phone, and he frowns as she puts it to her ear, taking it as a clear sign that the night is over. Casey does not take her phone out on dates. "Order for delivery," she says, stretching her legs out in front of her. She covers the receiver and glances across at Derek as he starts the car, "Chinese food is alright with you?"

"Great," he agrees, trying to keep his voice light. At least they will still be sharing a dinner? He listens as Casey places the order, and when he stops at a red light, Derek spares a glance at the passenger seat. She seems calm and relaxed, quietly ordering all their favorites—more food than strictly necessary. She's splurging.

When she hangs up the phone, she's beaming. "Food should arrive at the house not much longer than we will. I think we're beyond fancy first dates, anyway. We've known each other much too long to go through the whole ritual of getting to know one another." His lips tug up at the corner as she speaks, her hand tentatively reaching out to take his over the center console. "I just want to spend time with you."

Sometimes Derek forgets that he isn't the only one who has grown; that Casey has also matured.

Their date, which had started out so terribly, ends with comfy clothes, delicious Chinese food, and Casey and Derek staying up way too late talking—

—and kissing. There is lots and lots of kissing (though Casey won't let it go much further than that).

After that, things are smoother between them. That's not to say that it's easy; it still requires work and effort from them both, but they're more prepared for that aspect of their relationship. Casey and Derek each have strong personalities. Most of the time, they complement one another, but sometimes it means them clashing. They learn to communicate, though, in a way that makes sense to them both.

Some of their problems simply resolve with time and age. Casey decides they should attend couple's counseling. There are some issues that time alone can't heal. It starts because it quickly becomes apparent that Derek still holds some anger and resentment about missing the first part of Serenity's life. They can't go backward or change the fact, so it's something they both need to deal with. He wants Casey in his life, in this new-yet-old way, so it's something they—he—need to work through.

As much as Derek hates to admit it (though he will, when pressed), the therapy helps. Initially, he hadn't wanted to talk to a stranger about their problems. Casey had wheedled, begged, and pleaded. Ultimately, the desire to make sure their relationship lasts and a particularly unpleasant fight led him to agree. As Casey had predicted, the therapy helps in other ways, and they're doing okay together.

Initially, Casey hesitates in telling Serenity. She worries about getting her hopes up and things not working out, especially in the beginning. Once again, Derek reluctantly agrees it's a smart idea. He's impatient to have them be a family—a whole family—which Casey understands. She wants the same. But she knows how badly Serenity wants this, so they wait.

She should have predicted that Serenity would pick up on the noticeable shift between her and Derek after their first date. She's young, but she's never been stupid. Derek's hand lingers on the small of her back, her gaze staying on him for a few beats longer than necessary.

They go on dates sometimes, and Derek meets her for lunch when he can. Work picks up, and she's able to hire on some help. Casey makes a friend in the form of a colleague. Her name is Cheyenne. It's starting to feel even more like home in this new city.

Marti grows increasingly frustrated with Derek and his apparent refusal to act. As with their daughter, they decide to wait to tell their family. They need some time to themselves, some time to work through issues, and to learn to communicate without relying on intermediaries from their siblings. Derek was close to caving, though, when Marti lets the subject drop. She and Derek still talk, and she talks to Casey or asks how she's doing—so Derek informs her—but she aside from that, she doesn't push.

It isn't until five or six months into their fledgling relationship that they figure out why Marti lost interest. They had recently started discussing telling Serenity. It's still early on, but they've been doing well and are both committed to putting in the necessary work.

So, Casey comes home early on Friday afternoon, and they plan a family dinner. Serenity is thrilled to have her mom home early, and she dances around the kitchen, helping prepare dinner. Derek watches them from the doorway. It's just the three of them, so he can smile as widely as he likes. The only one who will tease him for it is Casey, but he's happy to take her light ribbing.

Eventually, dinner is ready, and they make it to the table. Serenity regales them with tales of her day, content in having both her parents' attention at once. In Derek's mind, the scene is perfect, and he looks forward to most nights being like this.

"Honey," Casey starts when it's clear that Serenity has finished telling them the important bits of her day. "There's something your dad and I wanted to talk to you about."

Serenity puts her fork down to glance between them. Her face furrows in concern. There's something so Casey about the whole thing that Derek bites back a laugh. "Is everything okay?"

The adults exchange a glance. Casey's nervous, but this is right, the two of them together. It's time to tell their daughter. "Yes, absolutely." Derek beams at her answer. Casey ignores him, focusing on Serenity. "It's just that we think—well, your dad and I—" she paused, her nose scrunching.

Serenity's eyes welled with unshed tears. "Are you and daddy breaking up?"

"What?" Derek blinked, eyes darting to Casey.

"No, we're not—" Casey leaned back in her chair. "We're getting together, dating."

"Oh." Dropping the tension in her shoulders, Serenity picks up her fork and returns to her food.

Once again, Casey and Derek exchange a look. It wasn't exactly the reaction they had been expecting. This time, Derek speaks up. "Are you okay with that?"

"Of course."

"It's, well," Derek appraises his daughter, "we thought you'd be more excited?"

Shrugging, she pierces a piece of chicken. "I was. I mean, I am. It's just old news."

"You knew?"

"Yup." The 'p' pops, and she sticks her fork in her mouth, smiling around it. Derek is, once again, struck by how smart kids can be. They shouldn't be surprised that she had picked up on the fact that things had changed between her parents.

"Okay." Casey glances at him, and Derek can see the way she deflates. Knowing her, she had prepared talking points, had prepared to discuss any concerns Serenity might have had. Serenity's blasé attitude had taken some of the wind out of her Mommy Sails even though it was a good thing Serenity was so on board. "And you don't want to talk about any of it? You're okay with everything."

"Of course." There is no doubt in her voice, only complete trust that her parents would not make a decision that would harm her. "Aunt Marti is thrilled, too." She adds.

Derek scratches his cheek and leans back in his seat, amused. At least now he understood why Marti had stopped pestering him about the situation. "Okay," he says, shrugging. Sometimes things were easy. The whole thing had been less painless than even he'd been expecting. Exchanging another glance with Casey, he shrugged, and the conversation moved on to what they were having for dessert.

After that, things pretty much follow a new normal. Once they are 'out' to their family—officially and for a second time—they see some involvement from their well-meaning parents and siblings. It comes as no surprise to either of them. They hadn't exactly stayed out of it once they found out that Derek was Serenity's dad, so them being out appeared to give them license to get more involved. It's okay, mostly, and having a sounding board in the shape of family turns out to be good for them. Casey, mainly, is accustomed to talking things out with her mom and Lizzie.

A few months after letting their family in on the secret, they come out to the public. Eventually, it would get out. They opted to be ahead of the story rather than needed to run damage control later. If it had come out in any way, but from them, it would look like they were trying to hide it, like there was something to be embarrassed or ashamed of.

The reaction is less severe than Derek, and his agent had prepared Casey for. The earlier reveal of Casey's parentage makes it easier. It had given people time to wonder, fixate, debate, and get over it, moving on to the next scandal. Their dating is, as Serenity had said, old news. Some people make a fuss about it, but for the most part, people are generally supportive or indifferent.

The important part is that the people who matter are on board. That's all she and Derek care about in the end.

A few years later, the family is gathered at Casey and Derek's house. It was, they'd told their family, for no special occasion. It was hard these days to get a day or weekend when everyone was free, but they had managed to nail one down. "We miss everyone," Casey had added, when trying to convince them to come to visit, "So we might as well snatch the opportunity." They'd been angling for a family get together that didn't fall on a weekend for about a month now, so the rest of them had agreed.

Not that there was a whole lot of reluctance from their family to begin with. Everyone gets in on Friday, and they spend the evening with take-out and catching up. It's casual, comfortable. Easy. Saturday, they decide, is going to be a Big Family Dinner. Derek invites Sam, and Casey asks Charlotte.

Marti is the first to notice that something is going on. While it isn't entirely unusual for Casey to dress up when having people over, even if they are just family and two close friends, she'd taken more care with her appearance than usual, including a light layer of makeup. Derek, too, appeared to be better dressed than one would expect; there wasn't a wrinkle in sight on his clothes. Serenity, also, had sat still long enough to have her hair curled. She'd have no luck getting an answer from Derek, so Marti goes to the weakest link.

"Is it so wrong that we wanted to look nice?" Casey bustles about the kitchen. She's making a big dinner, and there's a lot to do, but Marti gets the impression that Casey's avoiding meeting her eyes.

"It's just unusual."

Casey snorts. "You've been spending too much time with Lizzie and Edwin, reading too much into things." The doorbell rings. "Would you mind getting that?"

There are people much closer to the door, but Marti can see the dismissal for what it is. She scrunches her nose at Casey but heads to the door to reveal the night's second oddity. Standing on the other side of the door is a man Marti has never seen before. "Hi?"

He holds up a bottle. Champagne or wine, if she had to guess. "Might I come in?"


Before Marti can say much else, Derek joins her at the door. He brightens at the sight of the man. "Logan, come in. You're right on time. I just checked with Case, and dinner is nearly ready."

"Great." When Marti and Derek clear the space, Logan steps inside to introduce himself to the rest of the family and presumably drop off the bottle in the kitchen.

Marti tugs Derek's sleeve, holding him back. "Who was that?"

Derek blinks, looking down at her. "Logan."

Leaning back against the wall, she crosses her arms in front of her. She's never heard of this Logan before, and she knows everyone in Derek's life. She clarifies. "Who is Logan?"

"He's a new friend." Derek shrugs, already moving away. "We thought he'd like some company, so we invited him."

Derek is supposed to be King of the Lies. Marti knows this. She knew this at a very young age, so she studied him growing up. Marti learned to recognize his tells. She focused closely when he said something she knew to be true and said something she knew to be false. He's lying now. To her. And with a smirk.

There is, she concludes, a prank at play.

Dinner passes easily enough. Logan fits seamlessly into their group, as Casey knew that he would. Marti clearly suspects something, the way she keeps staring between her and Derek. Anytime someone clears their throat or shifts in their seat, her gaze shifts to them. Whatever she suspects, Casey is confident that it isn't correct. She starts to relax toward the end of the meal when nothing has happened, though there may be a small expression of disappointment.

When everyone is finished eating, Logan stands, helping Casey clear the table. This has all been planned out ahead of time. They return to the dining table where the rest of the family is still chatting; Serenity and Derek rise to greet them, moving to stand at the table's head. It takes a minute for the family to notice, and by then, Logan and Serenity are facing out toward them. Derek and Casey stand looking toward one another.

From the corner of her eye, she sees George lean in toward her mother. "What's happening?"

"I have no clue."

Marti blinks, her jaw dropping. "No."

Derek is full-on grinning now. Clearing his throat, Logan smiles and glances between them. "We are gathered here today," he starts.

"Oh." Nora fumbles for her phone.

"Is this—" Edwin cuts himself off, glancing around.

Casey can hear Sam's quiet, surprised chuckle. She can hear the whispers dying down, but she only has eyes for Derek. Beside them, Logan continues, "—the union of Derek Venturi and Casey McDonald."

Together they had planned this surprise wedding. If no one knew, there was no chance of it getting out. If they kept the affair small and intimate, they could get to be in the moment instead of getting distracted by wedding details that don't matter in the grand scheme of things. This way, it gets to be utterly theirs.

And, Derek is never one to turn down an opportunity for a fun prank, even if the marriage is legit.

The wedding is precisely everything that they wanted. It's short, sweet, with the most important people present. There are some notes of surprise that Casey is okay with something so simple. When she leaves to get the cake, Casey hears Lizzie ask Derek if she was really okay with the ceremony as it stood.

Derek laughs. "This whole thing was her idea—everything from making it a surprise to—" She can't hear the rest.

When she returns with the cake, her mom is laughing. She's relieved to find that no one seems all that upset at the deception. Mostly, everyone seems happy for them. Nora takes pictures as Casey and Derek cut the first slice of cake together. Later, Casey will find a fantastic shot of Derek, pretending that he's about to shove a giant piece in her mouth, followed by one where he feeds her a bite from a fork.

However, he does wind up smearing cake on her face, and she on his, but they also have their sweet moment. It's all very apropos.

Later, they're spread out around the living room. Derek is stretched out on the couch, and Casey is happily tucked into his side. Serenity starts to look a little sleepy, so she figures it's time for one less revelation. Nudging her daughter in the side until Serenity looks up at her, Casey smiles. "Your present," she reminds.

That wakes the young girl up. Serenity perks up and runs off. Hearing the commotion, Derek sits up, watching her go. "What's that about."

"I got her a gift," Casey says this loud enough for the family to hear and shrugs, stretching her feet out in front of her. "I want her to open it up while everyone is here."

He gives her an appraising look, and she works to keep her face neutral, a skill acquired during the practice of law. It's not very often she gets to pull something over on Derek. Before he can say anything, Serenity returns with a gift bag. There's various colored tissue paper peeking out from the bag. She drops back into the seat next to Casey.

"You didn't peek, did you?"

Serenity gives her such a look. "No." Though, the look on her face indicates that she had been tempted. Even now, Serenity was leaning a bit to try and see what might be under the tissue paper.

"Go ahead and open it." Casey smiles, glancing at Sam and Charlotte. They both already have their phones out. Yesterday she had called them up, asking for this one small favor. There was a good chance no one would realize what was going on—Nora and George had since passed the phase where they needed to photograph every gift that Serenity ever opened—but she wanted her family's reactions captured. Sam and Charlotte don't know what's happening, either, but they knew to take the pictures.

Serenity pulls out the gift. For a moment, her brow furrows in confusion as she starts to unfold the t-shirt. Casey had hyped up the present, and she could tell that her daughter didn't want to hurt her feelings and couldn't see what was so special about an article of clothing.

When it was open, her eyes widen, and she turns her gaze back to Casey. "Seriously?"

Casey laughs, nodding. They've now caught the attention of anyone who hadn't been curious before. Serenity throws her arms around Casey, squealing.

Sitting up, Derek smiles, amused as he picks up the shirt. Casey sees the moment he realizes what it means. There's a slight shine to his eyes—she's so glad that she was going to have pictures of this—his smile had gone from wide to small, but much softer. "For real?"

"For real." Casey nods again, happy that they are happy. He falls into their hug, and they get to enjoy this the three of them for a moment.

"What's going on?" Nora finally asks.

Serenity disentangles herself, grabbing the shirt back from Derek. Turning it around, she holds it up so the rest of the family can see what's on the shirt. Written in pretty, cursive letters are the words: Promoted to Big Sister.

a/n: The final chapter is here! It took me way longer to finish this than I had originally planned but life, as it does, got in the way. I'm going to spend some time looking at the projects I have published and incomplete and decide if I'm going to finish them or not. Then, I'll start working on some of the other projects I have pending. I'm on Tumblr now (isinkwiththeship). I post updates, snippets, and unrelated stuff. Lots of Dasey, though, if you're looking for extra content.

Thank you for everyone who kept up with this story. I loved all the comments. Happy reading, and keep a lookout for new work. :