It's two weeks before Halloween and Meredith and Derek are sitting in their living room trying to order costumes for Zola and Bailey.

"You ordered the navy scrubs for Zola right?" Meredith asks looking up from her laptop. "Yes. I'm just trying to find a lab coat in her size" Derek replies without even looking up. "You can't forget to put her name on it" she reminds him quickly before looking back down at her computer screen. He pauses and looks up at her before saying "why does she need her name on it, she's only going to wear it once." "Because our daughter is an attending and all attendings have their names on their coats, even residents have their names on their coats, because if our daughter is not even above the level of an idiot intern to you so help me Derek I will kill you." "I didn't even think of that Mer I'm so sorry. Our daughter is the greatest child surgeon in the whole universe and will have the best lab coat in the entire world" he says in a slightly mocking tone. Meredith looks at him in obvious annoyance. "Don't mock me this is very important." Derek smiles and tries to contain his laughter. He knows that her outburst is just due to her pregnancy hormones but he loves the fact that she is so passionate about this. "I'm not dear" he says kissing her on the head. Meredith turns to look at him and says "you better make this up to me with a lot of sex." Derek laughs a little and replies "I think I like bossy, pregnant Meredith she's very entertaining." Meredith shoves him a little and leans in to kiss him at the same time her does. Derek pulls away after a minute and smiles at his wife. "So what is Bailey going to be for Halloween?" "I think this year we make him a pirate" Meredith responds enthusiastically. "I love it!"

This year Jo made sure the house was ready, quite to Alex's annoyance. When the Shepherd family arrived they were greeted by jack-o-lanterns, spider webs, and Jo wearing a butterfly costume. Callie and Arizona had brought Sofia dressed as a ladybug. Four other families from the dare care were already inside playing games.

Derek walks into Alex's house to see Zola and Sofia eating candy apples and Meredith putting a pirate tattoo on Bailey's arm. "So sorry I'm late, motorcyclist with head trauma came into the ER and Amelia had already left for the night" Derek says as he comes up to his wife. "No worries" she replies giving him a quick kiss. "I think we're all ready to go trick-or-treating" Arizona exclaims as she walks in. The adults spend the next few hours chasing the kids around until Sofia and Zola collapse from exhaustion. Derek has already been pushing a sleeping Bailey in his stroller for 45 minutes when Meredith walks up and suggests they head home. On the car ride home Derek and Meredith enjoy the peacefulness that only happens when their kids are sleeping, and take the time to just talk about their days. Suddenly, Meredith starts shifting in her seat and looks like she's in pain a little. "What's wrong, is everything okay?" "Yeah I'm fine" she says with a grimace. "Your child has decided that now is a good time to break one of my ribs." "Oh, so it's my child now?" Derek asks playfully now that he knows she's okay. "When the fetus is kicking this hard, then yes it is your child." "Why are you still calling the baby fetus?' "Because 'the baby' doesn't have a name yet, or a gender" Meredith replies. "Well we can easily fix that. Let's just go in early tomorrow morning and find out" he says mater-of-factly. She smiles a little before saying "fine", and turning to look out the window. After a few moments in silence she looks back over at him, but quickly turns her head away. "What?" Meredith looks a little afraid of what she is about to say but blurts it out anyway. "What if we invited your family over for Thanksgiving?" "What if we did what?" Derek whips is head to look at her in complete and utter shock. "Keep your eyes on the road! I was just thinking it would be nice to see your mom, and Nancy and Lizzie already have plans with their in-laws so it would just be Kathleen and Amelia." Derek thinks for a moment before asking "wait, how do you know what Nancy and Lizzie are doing?" "I called them and asked" she replies confidently. "So you just decided that having my family over for Thanksgiving is a good idea?" "Yes I did." "Who are you and what have you done with my wife" he asks jokingly. "I just think it's time we stopped hiding out in the woods and face the fact that you have a huge family that is extremely mad at you for not visiting more often." Derek smiles and moves one hand off the steering wheel to hold Meredith's. "I think I like pregnant, married, happy you even more than regular married, happy you." "It's the kids they make me soft" she says with a smile.

Meredith is lying on an exam table with her shirt pulled up to expose her belly. Derek is standing next to her holding her hand while the OB is getting the ultrasound to focus on the baby.

"Are you sure about this?" Meredith asks Derek. "I'm sure if you're sure" he replies. "Well everything looks great to me" the OB says. "There's nothing wrong with the baby" Meredith says hoping the OB will reassure her. "Why don't you see for yourselves" she says. She turns the monitor around so Derek and Meredith can take a look, and they see a beautiful baby on the screen. They both break out into huge smiles, and Derek kisses Meredith's hand. "So you want to know the gender?" Meredith turns to look at Derek who nods encouragingly, so she says "yes, we do." The OB adjusts the ultrasound for a minute before saying "congratulations, you're having a girl!" "Fetus is a girl!" Meredith says excitedly. Derek laughs and leans down to kiss her before repeating "fetus is a girl!" They look lovingly at the screen for a few minutes until the OB prints out a few copies and Derek is paged into surgery. "I'll see you tonight for dinner?" "Yeah, and I think we have to tell the kids" she answers. "Whatever you want to do" he replies with a smile.

Later that night Derek is feeding Zola and Bailey dinner in the kitchen when Meredith gets home. He had told them on their way home that mommy has a surprise for them and Zola keeps asking for it every 5 minutes.

"Mommy!" Zola yells in excitement when she sees Meredith walk through the door. "Hi sweetie" she says giving her a kiss on the head, "and hi bailey how's my little man?" "Ma ma ma" he babbles as Meredith gives him a kiss too. "Mommy can I have my surprise now" Zola asks impatiently. Meredith gives Derek a confused look as Derek says "Zola remember what I told you the surprise is for you and Bailey." "Ohhh" says Meredith knowingly. "Zola do you remember when Bailey was born and he was a little baby?" "Yeah! He had no hair" she says with a laugh. Her parents laugh with her, and then Meredith resumes speaking. "Well in a couple of weeks we're going to have another little baby. You're getting a baby sister!" Zola sits in silence for a minute. She looks up at her parents and says "do I get to name her, and braid her hair, and play with her?" "Well mommy and I will pick her name but you get to do all the other things with her that a big sister gets to do" Derek says. Zola looks back and forth between her parents and then asks "where is the baby?" "The baby is in my tummy sweetie." Meredith takes Zola's hand and puts it over her stomach where the baby had been kicking earlier. As if sensing that her big sister is touching her the baby gave a strong kick right where Zola has her hand. "She kicked me!" Zola says in surprise. "That's how she says hello" Meredith tells her. "Hi baby" Zola says. "Mama has baby?" Bailey asks as he looks at his mom. "That's right Bailey you're going to be a big brother" Derek says. "Me big broder, me big broder" Bailey says with a smile.

After putting the kids to bed Derek and Meredith are finally able to relax. Meredith is sitting reading her book while Derek is changing clothes. "So I was thinking we could use one of our mom's names as her middle name" he says. "That's a good idea" she says, "but we should probably keep her first name options open because I'm probably almost going to die again and we'll have to name her after whichever one of our co-workers saves my life." "Meredith" he says in an annoyed voice, "that's not funny." "I'm just being realistic Derek, I'm a lightning rod for disasters and anything can go wrong when having a baby." "Seriously, I need you to stop" he says. "Everything will be fine." "It might all be fine in the end; I'm just saying you should be prepared to have a daughter named Richard." Derek laughs before climbing into bed next to Meredith. "Maybe we should just kick Richard, Hunt, and April out of the hospital for the day, just so we have a good chance of getting a good name. Oh and Bailey too because we can't have two kids named Bailey" she adds. "Fine" Derek says giving her a kiss. "We won't pick out any names until we know for sure she won't be named Avery or Calliope" he says with a laugh. "Thank you" she says with a smile. He turns off the lights and after a few minutes of trying to fall asleep she sits up. "I don't know if I could live with a daughter named Arizona" she says. "Oh would you just go to sleep."