A/N: Reminder that Callie and Addison were friends in Seattle earlier on in this fic. They didn't become friends until early season three of Grey's, but this story doesn't start until the end of season two and the first couple of episodes of season three. And if you don't remember, Callie and Addison don't even meet until 3x07.

A week later, Callie and Arizona arrived in LA. Before they got there, Addison gave them her realtor's number so they could find their own place. When they arrived at the airport, Addison met them at the airport. Derek would've joined them, but there was apparently a big car accident, so he had to stay at St. Ambrose instead.

"Callie!" Addison exclaimed when she saw her emerge from the crowd.

"Addison!" Callie matched her enthusiasm as she walked quicker to hug her.

"And you must be Arizona," Addison said after they let go of their embrace.

"Arizona Robbins. Nice to meet you," Arizona said, shaking Addison's hand.

"I can't believe this is really happening," Arizona couldn't help but say.

"I know," Callie said excitedly.

"I've been wanting you guys to meet for like, forever," Callie exaggerated.

"You know, she knew I was bi before I did?" Callie directed the question to Arizona as they started walking towards the exit.

"How?" Arizona asked giggling.

"She sounded like a 13-year-old with a crush when she talked about Erica," Addison informed her, referring to Dr. Erica Hahn.

"It's true," Callie confirmed.

"What did you say about the vagina monologues again?" Callie asked, laughing.

"The what ?" Arizona laughed along.

"I asked if you were speaking the vagina monologues," Addison giggled.

Eventually, the three of them made their way out of the airport. When they got in Addison's car, Arizona gave her the address of her new apartment. After that, they'd go to Callie's apartment. Before they left, they talked about if they should move in together. But at this point, they'd only been together for a few months. It felt too soon to live together. If they did, it'd be too much pressure. So, they decided they'd live separately. And if their relationship survived after a year of being together, they'd reevaluate.

"So, Callie said you went to Hopkins?" Addison asks as she pulls out of the parking lot.

"Yeah, I finished my residency there before I got to Seattle Grace," Arizona confirmed.

"You know, Derek has a sister that's going there. Or was. She just started her fellowship," Addison said, thinking of Amy.

"Any chance you know Amy? Shepherd?" Addison asked.

"Do you mean Amelia?" Arizona asked.

"Amelia, right. She goes by Amelia now," Addison said, making a mental note to make sure she'd remember.

"Yeah, I know her. She's great. She was my intern for a while before I transferred to Seattle," Arizona said.

"So, what do we need to know about LA?" Callie asked as Addison drove.

"The weather's nicer," Addison chuckled.

"Well, that was a given," Arizona commented.

"Right, well I don't know, it's more…relaxed here," Addison said, not knowing what else to say.

"You tellin' me you're Zen now?" Callie joked.

"Maybe a little bit," Addison giggled.

Eventually, they made it to Arizona's apartment. It was a nice quaint place, and the beach was close enough to walk to. She didn't have the beach as the backyard like Addison, but she would have a pretty nice view of the sunset from her bedroom.

"I could definitely get used to this view," Arizona observed the sun coming from the bedroom window.

"Yeah, this is gorgeous," Callie commented.

After they explored Arizona's new apartment for a bit and left her luggage in the bedroom, their next stop was Callie's place. It was a few blocks away and was relatively similar. They toured the apartment, as they did before, and then Addison drove them to St. Ambrose to check out the hospital.

Meanwhile, Derek was swamped at St. Ambrose. There'd been a big pile-up a few exits away and while he'd normally love a busy ER, he was playing administrator rather than surgeon today. And with the construction still ongoing, things were chaotic, to say the least. Plus, they had another neurosurgeon on call. With everything going on, Charlotte needed Derek's help by delegating rather than operating.

"Please, he won't stop crying," Riley whined to the nurse at the nurse's station as the baby in her arms cried and squirmed.

"I'm sorry. Will you hold on for a second?" The nurse was clearly busy with phone calls from people calling in to see if their loved ones were involved in the big accident.

Luckily, Derek caught sight of the young girl struggling with the baby. With things starting to settle down for now, he decided it'd be best to help the poor girl. She was young, alone, and didn't seem to know what she was doing.

"Hi, can I help you with something?" Derek asked, gently placing a hand on the girl's shoulder as the baby continued to cry.

"He won't stop crying!" Riley said, clearly exasperated.

"Here, why don't you let me take a look?" Derek offered, holding his arms out. Riley happily handed over the baby.

"Hey there, kiddo," Derek cooed at the baby, rocking him back and forth in his arms. As he did, the baby started to calm down a bit and rested his head on Derek's shoulder, his face still wet with tears.

"What's his name?" He directed his question at the girl.

"He doesn't have one…" Riley said awkwardly.

"I've just been calling him, baby," Riley admitted quietly.

"I don't know what to do. He's too little and I…I don't think I can do this," Riley felt tears coming but tried not to cry.

"Hey, it's okay," Derek placed a hand softly on her shoulder again while balancing the baby with his other arm.

"Have you thought about adoption?" Derek asked as the baby's cries started to calm down.

"What? Like, when you pick a family from the PennySaver?" Riley asked.

"The what?" Derek asked. He clearly didn't get the movie reference.

"The PennySaver. You know, like from Juno ?" Riley asked.

"Oh. Uh…no," Derek chuckled.

"In the real world, there are agencies that find parents who want to adopt babies," Derek explained.

"What if he ends up with a crappy family, though?" Riley asked.

"No, these agencies screen families so that babies will end up in nice, loving families to raise your baby," Derek continued.

"In fact, my wife's practice works with an adoption agency. I can get you in touch with them if you'd like," Derek added.

A few months prior, Dell convinced Addison (and Sam and Naomi) that it'd be a good idea to start working with an adoption agency. With the amount of money it'd bring to the practice, they couldn't refute that it was a good idea. And they even had a mostly successful test case, minus a little hiccup after the baby was born.

"But for what it's worth, I think you could be a great mother," Derek added.

He didn't want her to think that he saw her as a failing mother. Because he didn't. She was doing the best she could, but by the looks of it, whatever she was doing wasn't working. And not just because of how young the girl was. Her hair was greasy, her clothes were filthy, and Derek could even see specks of filth on her face.

It wasn't blatantly obvious, but up close, he could tell she'd been living on the streets, at a homeless shelter, or both. And that was no place for a newborn baby. But he wasn't about to point that out to a girl who clearly needed help. One that probably wasn't homeless by choice.

"So, these agencies," Riley started.

"Like, what exactly do they do?" Riley asked eagerly.

Derek then went on to describe how the adoption process worked. She continued asking questions that were admittedly a bit ridiculous. But she was a teenager who was clearly never counseled by a doctor beforehand about her options. After she finished asking her questions, Derek gave her a card for Oceanside Wellness, gave her the name of the adoption agency they worked with, and told her how the rest of the process would go. Or at least the parts he knew about.

When Riley told him she didn't have a phone to use, Derek offered the phone at the nurse's station. He would've stayed with her longer, but things in the ER were starting to pick up again. The baby was calm now and half asleep by now, and Derek handed him over, knowing that things would eventually be okay for Riley in the end.

As Derek and Charlotte struggled to juggle their responsibilities at St. Ambrose, Addison, Callie, and Arizona finally arrived. And Derek and Charlotte were relieved, to say the least. They could use both an ortho and a peds surgeon.

"Hey," Addison caught her husband as he rushed around the busy ER.

"Oh, hey," Derek said, surprised. The ER was so busy he didn't notice her and the other doctors come in.

"Arizona Robbins, Derek Shepherd," Addison gestured as she introduced the two.

"And you remember Callie, of course," Addison added.

"Hi, nice to meet you. Callie, good to see you," Derek said, shaking both of their hands, respectively.

"Any chance you guys can start now?" Derek asked, his voice slightly out of breath. He'd been running around all day dealing with everyone in the ER, as well as checking in with the construction crew periodically.

"Like now now?" Callie asked.

"Yeah, we could use your help," Derek confirmed.

"There's a kid who's having trouble breathing in bed four over there," Derek pointed.

"And a broken leg over in bed three," Derek pointed again to a man laying down with a brace holding his leg in place, clearly still in pain.

"Got it," Arizona and Callie said simultaneously before heading over to their prospective ER beds.

"Anything I can help with?" Addison asked, gently putting a hand on his shoulder. He looked exhausted and out of breath.

"I don't think we've gotten any pregnant patients yet," Derek thought for a moment. It'd been a pretty hectic day already.

"No, I mean for you," Addison rubbed part of Derek's shoulder with her thumb.

"I'm fine," Derek waved her off, still thinking about what else had to be done to keep the ER in order.

"No, you're not. You're practically out of breath. You need to sit down for a minute and drink some water," Addison insisted.

Then she grabbed hold of one of his hands before leading him to sit down. After he sat down, Addison got up to get him a cup of water.

"Drink. Breathe," Addison instructed. Derek did as he was told.

"Thanks," Derek said, his voice sounding more even now.

"I know it's hectic today, but you need to take care of yourself too," Addison said. Derek nodded before taking another sip of water.

"If not for you, then for me," Addison jokes, making him crack a smile.

"Deal?" Addison asked.

"Deal," Derek agreed.

"Finish that before you get back to work," Addison pointed to the half-filled cup of water before giving him a quick kiss.

"I'll see you later. And call me if you need an extra hand here," Addison added before leaving.

"I love you," Derek raised his voice as she walked away. She blew a kiss back before disappearing around the corner.

The busyness of the ER finally died down a couple of hours later, thankfully. Injured patients for the help they needed, the ORs were full, and while a big accident wasn't something to celebrate, it did, however, make the board happy.

And with all the work and money Derek was putting into building St. Ambrose's reputation, as well as expanding the overall hospital, things were looking up. But despite the hectic day, Derek, per Addison's advice, made sure to take short breaks to breathe and hydrate in between the chaos.

"You know, when Addison told us about this hospital, we didn't realize such a small place would be so busy," Callie said, catching Derek in the hallway.

"Yeah, it comes in waves," Derek said.

"Hey," Arizona greeted them as she rounded the corner.

"Your residents are great. No wonder you believe in this place," Arizona said after giving her girlfriend a quick kiss.

"Yeah, they are," Callie agreed, also impressed by the St. Ambrose doctors.

"Thank you. We're still a little short-staffed, but I appreciate you guys coming out here," Derek said.

"Of course," Callie said.

"After everything Addison's done for me, I'd do anything for her," Callie added.

In Seattle, just like how Callie was Addison's only friend, she was the same for Callie. Izzie made it hard for her, with her possessive behavior toward George, which also extended to the other interns. And it made it hard for her to make friends. Addison was the only one that didn't let it phase her. And their case of a stillborn baby only brought them closer.

"Hey," Mark caught up to them as he got out of the OR.

"You two must be the new transplants," Mark referred to Callie and Arizona walking alongside Derek.

"Callie Torres, Arizona Robbins, Mark Sloan," Derek gestured as he introduced the three.

"My pleasure," Mark jokingly took a small bow.

"Oh, so you're Mark," Callie said. Addison told her about him. She knew better than to fall for his womanizing ways.

"Watch out for him," Derek joked before they went their separate ways.

After another two weeks, St. Ambrose hospital's construction finally finished up. The construction guys ran into some plumbing problems, postponing the completion date by another week. But everyone was relieved that the noise and closed corridors were finally over.

Callie and Arizona settled into their new lives nicely, as Derek's plans for the surgical residency program started. He, Charlotte, and the board went through the process of recognizing the program with the Medical Accreditation Association as a legitimate program. Thankfully, some interested med students applied after they marketed the new program online. Paired with the impressive new doctors and building expansions, their new program was almost ready to start.

When Derek came home at three in the morning yet again, Addison convinced Charlotte to give him a night off. He needed a break and, more importantly, some sleep, after months of working himself ragged. Plus, Addison missed having someone in bed next to her. And when Addison told him that last detail, Derek agreed it'd be nice to have a night off to be with his wife.

Plus, he didn't want to fall into the same pattern he did back in New York. Mark and Addison's affair may have been why he left, but he knew that it didn't just happen overnight. He'd been working nonstop in New York too. No wonder Addison got lonely. While he, Mark, and Addison were all on good terms now, he didn't want to give them a reason to repeat that mistake. And he definitely didn't want his wife to feel like he didn't love her anymore. Which, admittedly, is how he made her feel in New York after years of being dismissive.

On Derek's night off, he and Addison went out for dinner for a change at a nice restaurant and even asked Callie and Arizona on that double date they owed them. It'd been a while since he dressed up for dinner, since New York, actually. And back then, he dreaded it. But now, he was happy. Now, he looked forward to it. And when he saw Addison in a skin-tight, long-sleeved, black dress with a large slit in the back. It showed off her fit figure well, and she looked incredible.

"Wow," Derek said as Addison descended the stairs.

"Thanks," Addison blushed as she finished putting on her earrings.

"You don't look so bad yourself," Addison added.

Derek wore a very light gray suit with a tucked white dress shirt and a loose black tie hanging around his neck. He shaved a little more tonight after letting his facial hair grow more over the past few weeks from sheer exhaustion. His dark hair had specks of gray hair in them, but his eyes were still a deep blue, matching the ocean in their backyard.

After Addison finished messing with her earrings and putting on her designer shoes, she walked up to help adjust his tie. As she did, it surprised her to feel his arm wrap around her waist, pulling her closer until their lips touched. After letting the moment hang in the air for a few more minutes. Then, they both made their way out to the car and met Callie and Arizona at the restaurant, who also both looked beautiful, all dressed up.

It was a nice, quiet night, and Derek finally felt fully relaxed for the first time in months. The conversation was light and fun. They all traded stories about their tiresome and ambitious residency days. Derek asked Arizona about Amelia and she raved about how great of an intern she was. She was smart, focused, and ambitiously fierce. And she clearly looked up to her brother as she focused on specializing in neuro. Callie and Addison unsurprisingly found common ground when talking about their childhoods. Addison's trust fund was much larger than Callie's, but their experiences with hired help and family friends had a familiar feel to them.

Derek and Arizona teased, and the whole night in its entirety was a nice relief from all the pressure that'd been weighing down on Derek's shoulders over the past few months. The hospital was in great shape: the construction was over and the surgical residency program was about to start the next few weeks.

When Derek and Addison came home, Derek swooped her up in his arms and carried her upstairs. It'd been a perfect evening. And making sure his wife knew how much he loved and appreciated her only made it better. However, Derek didn't end up getting a full night's worth of sleep like Addison and he both wanted. At almost two AM, the phone rang.

"Hello?" Addison answered the phone as Derek groaned, checking the clock.

"Excuse me? Yes, yeah, okay," Addison sat up immediately. Derek was still half asleep, but feeling her jerk upward caught his attention. She too liked getting her sleep, so it had to be something important if she was getting up for it.

"We'll be right there," Addison said before hearing the other end hang up.

"You do see the time, don't you?" Derek asked, his eyes still shut.

"Derek, get up. We have to go." Addison gently pulled the blanket off him, which she knew he hated. But she also knew it was the best way to wake him up in a hurry.

"Why" Derek groaned, turning over to face her as he rubbed the sleep out of his eyes.

"That was Cheryl," Addison said as she made her way to the closet.

Derek, much like Addison earlier, pulled himself up and started getting ready after giving himself a minute for everything to sink in. Cheryl was their social worker. It may be the middle of the night, but they might actually get their baby. Waking up in the middle of the night on his first night off in a long time would be well worth it if they could take a baby home by the end of it.

"What'd she say?" Derek asked, pulling a pair of jeans over the boxer pants he wore to sleep.

He didn't want to get her hopes up, but she couldn't help it. At this point, it'd been so long since they'd heard from Cheryl that they were both even more desperate to become parents now. If that was even possible.

"She wants us to meet her at St. Ambrose," Addison said.

After they both got dressed, they rushed over to the hospital. On the way, Derek asked every question he could think of. But Addison didn't have any answers for her. All Cheryl said on the phone was that a birth mother chose them from a book of prospective parents and that the baby had already been born. She wanted to ask her more questions, but Cheryl was quick, efficient, and hung up immediately after confirming that she and Derek would meet her at the hospital.

"Cheryl," Addison said after seeing her in the hallways of St. Ambrose.

"We got here as fast as we could," Derek said.

"Mm-hmm. Traffic, I know," Cheryl said as she began walking down the hallway, with Derek and Addison following closely behind.

Both Derek and Addison usually appreciated this no-nonsense attitude from Cheryl, especially since it made the overall process easier at times. But they both felt a little frazzled at the moment and would prefer a little more information than what she'd given them so far.

"It's just, we hadn't heard from you in a while, you know, and we just assumed…," Addison rambled.

Both Derek and Addison were desperate for a baby, but playing the waiting game was torturous. And after a while, they didn't know if they'd ever become parents.

"...Anyway, and uh, to get a call so late," Addison kept rambling, but stopped when she felt Derek's hand squeeze hers. When she looked over at him, he gave her a small smile.

"This won't be the last time a baby wakes you up late at night," Cheryl added, as they all kept walking.

"Mother delivered a baby a few weeks ago and won't be able to keep him. Thinks you're a good fit," Cheryl said.

"Him?" Derek couldn't help but blurt out. The baby, their baby, was a boy. He couldn't help but think that they were about to meet their son.

"Mm-hmm," Cheryl confirmed.

"Wait, she thinks we're a good fit? Wait, us? Okay, we're a good fit?" Addison asked anxiously.

Derek squeezed her hand again to try to ease her a bit. He was just as nervous as she was, but Addison had a tendency to ramble, whereas Derek stewed internally. After over 12 years of marriage, it became a constant balancing act between the two.

"Birth mother went through the book of prospective parents, chose you, wants to see you," Cheryl added as they finally reached the door to the birth mother's room.

"Uh…okay," Addison said as she began trying to fix her slightly messy hair. Derek couldn't help but chuckle.

"You wanna comb your hair? Or do you want a baby?" Cheryl finally asked.

Addison and Derek looked back at Cheryl wide-eyed, signaling that they indeed wanted a baby. Cheryl opened the door to reveal Riley, Addison's patient from weeks prior. And the girl Derek helped a few weeks ago.

"Riley?" Derek and Addison asked in unison. They both looked back at each other, shocked that they both knew the girl.

"How do you know her?" Derek asked.

"I…delivered her baby," Addison revealed.

"What about you?" Addison asked curiously.

"I helped her get set up with the agency," Derek said. They both laughed at the irony of it all.

"I couldn't believe it when I saw your picture. I figured it must be like, meant to be or something, right?" Riley said.

Addison's face broke out into a bigger smile than before as she squeezed Derek's hand a little tighter this time. When she looked over at him, he saw his smile was just as big as hers.

"Do you wanna hold him?" Riley asked.

For some reason, Addison couldn't say "yes" out loud, but she could tell her answer by the look on her face. Derek and Addison moved closer to Riley, who stood holding the baby. This baby was perfect. Addison couldn't help but remember about his cracked clavicle at the moment, but she also knew it'd heal completely in a couple more weeks.

Then, Derek and Addison took turns holding the baby. Despite this baby being almost a month old, he still didn't have a name. Now that this baby was going to be theirs, Derek kept pushing for the name Christopher. Addison wasn't completely against the idea, but she wanted another option. She still wanted his name, his full name, to have some significant familial meaning. The Forbes Montgomery name had weight to it. One that she carried with an immense amount of pressure for her entire existence.

But this baby would be a Shepherd. She wasn't sure if she wanted him to tack on Forbes Montgomery as well because regardless of what this baby's name would be, "Forbes Montgomery Shepherd" or even "Montgomery Shepherd" was a mouthful. But she survived with that mouthful of a last name, Forbes Montgomery, for a long time. And now she was technically a Forbes Montgomery Shepherd and had been for over 12 years. So if she could handle it, so could their son, she thought.

But she wanted his first name to be his own. Christopher, or even Charles, her father's "real name", could be his middle name. Or both if they wanted to give him the longest full name ever.

After letting the baby get some sleep in the incubator, they went back to talk arrangements with Cheryl and the birth mother. Addison wanted an open adoption, and after some back and forth with Derek, he finally agreed.

"So, what happens now?" Derek and Addison entered the room as Riley and Cheryl talked.

"Well, it's an open adoption, so it means you'll have a role in the baby's life," Cheryl explained.

Derek and Addison watched as Cheryl continued explaining the overall process. It surprised them to learn that Riley still knew next to nothing about adoption. Despite the fact that she was putting her baby up for adoption.

Everything she did know was what Derek told her a few weeks ago. And she almost recited it verbatim the way he told him. So, for all he knew, she had no idea what she was talking about. She was so far out of her depth; it was unexpected. But then again, Addison sensed this girl was exceedingly unprepared when she delivered her baby.

"Wait, so I'm gonna get to see my baby grow up?" Riley asked.

"Well, open adoptions are negotiable. It's just a matter of deciding what makes each of you comfortable," Cheryl explained.

"What if I don't know what makes me comfortable?" Riley asked.

"Like, what if me being in this kid's life is just gonna screw him up?" Riley asked.

"It won't," Derek said.

He didn't know why he said it. He barely knew the girl. For all he knew, she could screw him up. But it felt like the right thing to say. And this girl didn't seem like she'd purposefully do any harm. She was young and by the looks of it, without means. Did she even know where she was going after this? Neither Derek nor Addison knew the answer to this, but they were stunned that she was even able to put this baby up for adoption at all.

"How do you know? You barely know me," Riley said back.

"You're right, we don't. But we know that you're doing the best that you can for your baby," Addison answered for Derek when he struggled to find the right words.

"So, what are we naming him?" Derek asked. He was still set on the name Christopher, but after Addison explained her reasoning, he agreed to be more open to the idea of a different name.

"We can't just take no-name here home without a name," Derek joked. Addison giggled back.

"What about Nathaniel ?" Addison asked, gesturing with her hands as if the name were appearing in front of them.

"Nathaniel," Derek repeated the name.

"Nathan," Derek looked curiously down at the baby still pondering on the name.

"Nate," Derek said.

The nickname was something that appealed to him more. Nathaniel felt more regal than it needed to be. But then again, he could tell Addison liked it. And he doubted anyone, other than maybe Bizzy and The Captain, would call him by his full name. It was like the perfect compromise. Nathaniel was the WASP-ier name, while his nickname, Nate, grounded him a bit more.

"I like it," Derek finally said.

"Really?" Addison's eyes lit up.

It'd been almost two years of trying to adopt a baby. And for most of that time, both Derek and Addison exchanged name ideas. None of them ever really felt right though. Addison was adamant that she'd know when the baby came. She wanted whatever name their baby would have to fit him or her. She didn't want them to have their eyes set on a name only for it not to fit.

"Yeah," Derek smiled back as he loosely put an arm around her waist.

"Nathaniel Christopher Montgomery Shepherd," Derek said.

Addison chuckled knowing that it wouldn't be Derek if he didn't at least try to sneak Christopher back in there. But she had to admit it sounded nice all together like that. Plus, the fact that it was also Derek's middle name gave it that much more meaning.

"Nathaniel Christopher Montgomery Shepherd," Addison repeated as they both leaned in for a sweet kiss.

After having some alone time with baby Nathaniel, they let Riley say her goodbyes in private. Although, they did so after informing Riley and Cheryl of his new name. As Derek and Addison stood in the hallway, excited to bring him home, they saw Mark with a teddy bear wearing a small baseball cap in one hand and a bouquet of flowers in the other. Derek texted Mark in the car as Addison drove, letting him know what was going on.

After their relaxing dinner date, Derek checked in with Charlotte and she let him know there was a big fire in the valley. So, Derek assumed Mark would still be at St. Ambrose with whatever burn victims came in that night.

"Am I the best uncle or what?" Mark shouted down the hallway when Derek caught sight of him.

"What the hell is this?" Derek asked, laughing.

"The bear's for the baby, the flowers are for you and Addie," Mark explained as he handed Derek the gifts.

"Thanks, man," Derek said, roping Mark in for a hug.

"So, how's the kid?" Mark asked.

"He's…perfect," Derek couldn't help but say.

"Other than the cracked clavicle," Addison couldn't help but add. Her nerves and excitement were still getting the better of her. Plus, this wasn't a surprise to Derek because she told him earlier about the delivery when they had their alone time with baby Nathaniel.

"Is he alright?" Mark asked.

"Yeah, he's fine. It was the only way to clear the birth canal," Derek said. It sounded weird coming out of his mouth.

"Or so I'm told," Derek added, leading them all to laugh along.

Being married to Addison definitely came with its quirks. Saying things like birth canal like it was a normal thing was one of them. When they got back to the NICU where Riley held the baby, all three of them watched her say her parting words to baby Nate as Cheryl stood in the corner.

"You're gonna have such a great life with these people," Riley whispered.

"Just try not to cause too much trouble," Riley added as Addison giggled at hearing this.

Riley handed the baby to Addison's waiting arms and when she did, she looked up to see not just Derek in the doorway, but Mark as well.

"Wow," Riley said, looking at Mark.

"It's just a little gift from Uncle Mark," Mark said proudly, thinking Riley was referring to the gifts he was holding.

"Uncle?" Riley couldn't help but interrupt.

"Yeah, I'm Mark Sloan," Mark held out a hand for her to shake. Something about her felt familiar, but he couldn't explain why.

"My husband's best friend," Addison explained further.

"It's really you," Riley couldn't help but say.

"What do you mean?" Mark asked, confused.

"Do you two know each other?" Addison asked.

"Don't tell me you're our baby's father," Derek joked.

"What? Ew no," Riley blurted.

"Ouch," Mark said, slightly insulted. Then again, this girl was clearly too young even for him. She was a teenager, and that was territory Mark would never try for.

"I just mean…," Riley stammered for a minute.

"My name's not really Riley. Well, it is, it's just…it's my last name," Riley started.

"My name's actually Sloan Reilly…and uh, my mom's Samantha Reilly, and um…I'm pretty sure you're my dad," Riley blurted out.

A/N: Surprise! I'm really sorry I'm leaving all of you on a bit of a cliffhanger this time, but I just couldn't wait anymore to give Derek and Addison their baby. Plus, as I've said before, I do have more ideas on this fic. But I'm also really hoping you guys didn't see this coming. Thanks again to Stephanie for letting me bounce me off of you and I promise not to make all of you wait too long for the next chapter update. Let me know what you thought of this twist in the comments/reviews or tweet me mzsnguyenthai. Until next time!