A/N: Alright, so this idea randomly came to me today and I had to get this first chapter written out.

Full summary: Beckett is enlisted by Captain Gates to act as babysitter to the two children of an important witness about to testify. With Castle out of town at a convention, and Ryan and Esposito serving as part of the witness's protection detail, it leaves Beckett on her own to deal with the two young kids. And all of her tough NYPD Detective resolve may not be enough to get her through a day with two kids who don't appreciate having a strange new sitter thrust upon them and are making that fact obvious to Beckett in the worst possible ways.

Okay, so the plan is to have this story end up being around 5 or 6 chapters. But I'm still coming up with prank ideas for it (yes, Beckett will be getting pranked by these kids), so we'll see how long it is til the next update (I'm also working on another story at the moment). I already have a few ideas planned out, but I'm willing to hear any from those of you who happen to read this and get a few in mind; just PM me if you get any prank ideas. And don't be afraid to hold back. ;)

Also, yes - I'm planning on bringing in Castle via phone chats.

Anyway, for now, enjoy this introductory chapter! :)

Chapter 1

Beckett the Babysitter

"It's just that I'm still a little unsure about this, that's all," said Emily Downey, a middle-aged woman with blue eyes, curvy features and brown hair through which she was currently running her fingers out of slight nervousness. She was standing just inside the entrance to her spacious two-story home in Long Island, surrounded by four members of the NYPD.

Those four members were Captain Victoria Gates and Detectives Kate Beckett, Kevin Ryan and Javier Esposito, and all of them had reassuring expressions on their faces.

"Mrs. Downey, I more than understand your hesitation," Gates began with a soothing tone, "but you getting on that stand and testifying today is absolutely vital. Your husband is secure at an undisclosed location, as you know, but we need to make sure your children are also safe in order to avoid any possibility of intimidation."

"Do you really think that could happen?" Mrs. Downey asked, fear making her voice crack.

"The Mob has a long history of getting to witnesses," Esposito informed her. "And we've learned from experience it's best to cover all options."

"Once the jury reaches its verdict, you'll have nothing to worry about," said Gates. "But until then, we're not taking any chances."

Mrs. Downey looked to Beckett, who was looking back at the mother in sympathy. "Do you have a lot of experience with children, Detective?" she asked.

"Uh, I did some babysitting as a teenager," Beckett replied with confidence, "and I remember enough from then that I can promise you that your children are in safe hands either way, Mrs. Downey."

Her words appeared to calm Mrs. Downey, as the mother let her fingers fall out of her hair. "Okay, but I still don't get why I can't tell my kids that it's a cop who's watching them."

"It's better not to worry them," Ryan spoke up. "For all intents and purposes, Detective Beckett here is just a replacement sitter filling in for their usual one."

Gates glanced down at her watch. "We have to be at the courthouse in just under an hour, so we'd better get moving. Mrs. Downey, I suggest bringing your children down to meet Detective Beckett, then we can be on our way."

"Of course, I'll be back in a minute," said Mrs. Downey before she parted company with the cops and ascended the nearby staircase.

Once she was gone, Gates turned to Ryan and Esposito. "In the meantime, why don't the two of you go and get the rest of the detail ready? We'll be out soon."

"Yes, sir," Ryan and Esposito both responded simultaneously. On their way out into the cloudy day, the two Detectives gave their partner encouraging looks, which Beckett answered with a grateful smile. This left Gates and Beckett alone.

"Detective, I realize this isn't exactly a plum assignment," Gates told one of her best employees, "but I appreciate you agreeing to it all the same."

Beckett nodded. "It's really no trouble at all, sir. Whatever I can do to help. Besides, as you pointed out, it is a necessary precaution."

Gates smiled with respect. "That's the kind of attitude I like to see, Detective." The sound of footsteps drifting down from upstairs drew both of their attention. "I'll leave now so you can meet the children. But make sure to keep your phone nearby at all times, because either I or Detectives Ryan and Esposito will call with updates. And, you remember the combination to the safe."

Gates gestured over at a painted picture of the New York City skyline, behind which was a safe where Beckett had stowed her weapon and badge upon arriving. Not only did it help maintain Beckett's "cover", it also kept her gun out of the kids' reach.

"Yes, sir, I do. We'll all be fine in case anything should come up."

"Good luck," said Gates with a pat on Beckett's shoulder before she exited through the front door. And just in time, too, because down the stairs came Mrs. Downey, accompanied by two boys. The one on the right wore a turquoise shirt with khaki pants while the one on the left had on a brown shirt with jeans. Like their mom, each boy had a mop of brown hair. Neither of them looked older than ten.

"Boys, this is Miss Kate Beckett. She'll be watching you today while I'm out," Mrs. Downey announced once they had reached the ground floor. "Kate, this is Brad, age eight" she said, indicating the boy in turquoise, "and this is Sean, six," she finished, touching the shoulders of the one wearing brown.

In that instant, a slight feeling of nervousness overcame Beckett as she could feel butterflies in her stomach. She'd never been alone with kids of any age in years, and the implications just now dawned on her. Nonetheless, Beckett put on a friendly smile as she bent down to look the kids in the eye.

"Hi, I'm Kate!"

Brad shot her a blank stare before looking up at his mother. "But, Mom, why can't Rachel look after us? We love her!" That made Beckett's smile falter slightly.

"Boys, I told you, Rachel couldn't make it today because of family issues. So, I got Kate to watch you. Don't worry, you'll like her."

"Yeah, right," Brad grumbled into his shoulder, which made Mrs. Downey shake his shoulder reprovingly.

"I know I'm not what you expected," Beckett said gently, "but I promise we're going to have some fun!"

"How does Mom know you?" Sean asked in a kind of tone Beckett could compare to an interrogator questioning a suspect.

"Um," stalled Beckett, quickly thinking on her feet, "she ... met me at work."

From the looks Brad and Sean were giving her, Beckett couldn't tell whether they were buying it or not.

"Okay, that's enough questions," Mrs. Downey cut in. "Be nice. Now, boys, I want you to be on your best behavior for Kate and do what she says. If my ... meeting goes well, then I should be back by dinner." Brad and Sean nodded silently and Mrs. Downey kissed each of them on the cheek. "I love you, and I'll see you later."

She left them standing in front of the stairs while Beckett straightened up.

"Thank you," Mrs. Downey added genuinely as she buttoned up her coat.

"You just go and do what you have to do," said Beckett vaguely. "We'll be waiting for you when you get back."

Mrs. Downey nodded, turned to her boys to blow them one last kiss and then stepped through the main doorway. Beckett closed the door behind her, locking it for good measure. This left the house in an uncomfortable silence, made even more uncomfortable when Beckett turned back around and noticed Brad and Sean just staring at her. Beckett considered herself very adept at reading people, but those were fully-grown people and not little kids who were currently giving her an uneasy feeling. What was it about them? Suddenly, she found herself wishing that Castle was here to lend her some help, instead of at a mystery fiction convention in North Carolina.

Come on, Kate, you've gone up against some of the worst criminals and murderers this city has to offer. Why are two kids making you so nervous?

"So, um, what would you guys like to do?" she asked in a conversational manner.

After what seemed like an eternity, Brad and Sean, as one, smiled widely at Beckett. But it wasn't much better than the blank looks they had already given her, because these smiles were just as unreadable.

Maybe it would've been safer on Mrs. Downey's protection detail.