A/N: Welcome, welcome my friends, to my first ever Sherlock fic! I'm so excited about this. I hope you enjoy it!

Disclaimer: The semester is almost over! Whoo!

"Now, are you completely sure about this?" John Watson asked for what felt like the millionth time.

"I believe I have repeated myself sufficiently," Sherlock Holmes replied in his usual acerbic manner. "I will be perfectly fine. We," he emphasized, gesturing to the baby in his arms," will be perfectly fine."

John paused in the doorway of the flat he once more shared with his best friend. After Mary was killed, he couldn't bare to stay in their house. While he didn't want to take Rosie from her home, John felt too confined there, as though he couldn't move on when surrounded by so many memories.

That was why Sherlock invited (forced) John to move back to 221b Baker Street. Knowing he would need help with Rosie, John agreed (submitted) and a few days later, he and Rosie were living with Sherlock.

"It's just that you've never actually kept Rosie by yourself before."

"Have you so little faith in me, John?" Sherlock feigned disbelief as he exchanged glances with his goddaughter. "When have I ever let you down?"

"Do you really want me to start a list?"

"That won't be necessary," the other man assured him. "Just go, John. You'll only be gone for a couple of hours."

The smaller man stared at his tall friend for a long moment. "I'm sure I can just call Molly or Lestrade. They won't be that busy at work."

"You're going to be late for your appointment with the new therapist."

"Fine!" With jerky movements, John grabbed his coat from the coatrack. "You better be right about this, Sherlock."

"Rosie has been fed, changed, and had a nap. I believe I am capable of playing with her for a couple of hours."

John rolled his eyes. He couldn't deny any of it. "Just promise me, no experiments involving my daughter," he begged.

"I would never," Sherlock argued in a tone that betrayed his plans to do just that.

"No experiments!"

"What would I get in return?"

"I won't shortsheet your bed."

"That's boring."

"I won't stuff your pillow with the body parts currently occupying the refrigerator."

"Still boring."

"I'll let you do an experiment with me AND Rosie once I get back."

This caught Sherlock's attention. "You can't back out of it at the last moment."

John rolled his eyes. "I promise, as soon as I get back from my appointment with Dr. Freeman, I will let you conduct an experiment with me and Rosie as the test subjects. Within reason."

"Excellent. Now, off you go. Don't be late." With a wide grin that promised nothing but trouble, Sherlock carried Rosie across the room and settled them both in Sherlock's chair.

John sighed as he walked out the door. "I'm going to regret this. I know I'm going to regret this."

The smile transformed into a smirk as Sherlock watched his roommate walk out the door. "Now, Miss Rosie, what shall we do while Daddy's not here?" With gentle hands, he shifted Rosie until she was standing on his lap. "What kind of trouble do you think we can cause?"

"Ah bah doh doh doh," Rosie answered as she reached out toward Sherlock, her tiny hands mapping out the planes of his slender face.

"I had exactly the same thought. Nerf guns it is."

The pair spent a pleasurable time shooting the apartment wall with the Nerf guns Sherlock had recently bought with John's credit card (not that John knew about them, of course). Rosie thought it hilarious when the bullets hit the yellow smiley face, and her chubby little hands clapped every time.

"If I had known you would find it this enjoyable, I'd have brought out the Nerf guns months ago," Sherlock mused as he hit the face once more, causing the baby he held to giggle yet again.

Eventually, both of them got tired of shooting at the wall, so Sherlock set her on her blanket with a few soft toys to play with for a while. "Alright, you stay here for just a few moments. I have to look over a potential case for Uncle Straddy. It is likely to be a waste of my time, but I shan't know that for sure if I don't read it, yes?"

"Mba," was Rosie's answer.

"Exactly. Uncle Straddy should hire you. The police might actually solve a case on their own for once. I shall be right back." Handing Rosie her favorite stuffed animal, Sherlock regained his feet and moved to the kitchen, where he'd left the case file.

Just as he was getting to the crime scene evidence, a cry was heard from the living room. "Now, what could be the matter in here?" Sherlock asked the baby as he knelt before her. She just looked up at him with her bright eyes. "You shouldn't be hungry, as you just ate less than an hour ago. Shall we see if you need changing?" Standing the little girl up on her feet, Sherlock checked to see if she needed a new diaper. "Clean." He set Rosie back down so he could talk to her. "You're not hungry, you don't need changing, you've had a nap. Would you mind telling me what it is you require?"

Rosie continued to just stare before batting her hands at the teddy bear lying beside her. "Well, I suppose that means you're alright?" the detective asked uncertainly. Keeping a suspicious eye on her, Sherlock stood back up and took the case file from the table beside John's chair. Before he could begin reading again, Rosie let out another cry.

"Rosie, dear, whatever is the matter?" he asked as he joined her on the floor again. "There is no logical reason for you to be crying. Now, tell me what the matter is, please." A tiny hand reached out to latch onto Sherlock's pants. "And what does wrinkling my trousers accomplish?"

More crying followed.

"I really would like an answer, love. Can you please give me an answer?" Even his best puppy eyes didn't get Sherlock what he wanted. "Do you want a different toy?" The detective reached a long arm out toward the table by his chair and dragged over the bin where they kept Rosie's toys. "Here is your rattle. I'm not entirely sure why we still have that, but here it is. Would you like that?" Rosie took the rattle from the man and examined it in her tiny hands for a moment. "See now? Isn't that better?" He was answered with the rattle hitting him in the face. "I thought we went over this before, young lady. As you obviously do not want the rattle, we must find what it is you truly want. Now, is it something in this room?"

Once more, Sherlock stood and looked around the room, trying to deduce what exactly is was that Rosie wanted. As soon as his back was turned, though, she started crying again. Only, it wasn't small whimpers anymore. Now, she was fully crying, with tears streaming down her chubby cheeks.

"Oh, no, no, Rosie. Don't do that," Sherlock begged. On the edge of panic, Sherlock knelt back down and gathered the baby in his arms. As soon as she was settled against his chest, she stopped crying. The detective was taken aback. "Why have you now decided to stop crying?" he asked her. He didn't get an answer, of course. "Well, seeing as you have stopped crying, would you like to play on the floor again?" Very gently, Sherlock set Rosie back on her blanket. Her little hands held onto his, her fingers tightening around his as he tried to let her go. "It's alright, Watson. Just have fun with your blanket."

However, as soon as he removed his hands, Rosie began crying. "What?" Sherlock panicked. "No, no, you were fine mere seconds ago." Wanting to make the crying stop, he lifted Rosie back into his arms. Just as before, Rosie stopped crying as soon as she was settled against her godfather's chest. "This is highly illogical, you do know this?" Rosie stared at Sherlock, her eyes wide as she listened to him talk. "For what reason do you need me to hold you? There is nothing ailing you, you have been fed and changed, you do not need a nap. I do not understand why you want me to hold you." Soft baby babbles were Rosie's answer, punctuated with a hand slapping lightly at her godfather's face. "It would seem you have something to discuss with me. Shall we take this to the couch?"

Carrying the baby across the room, Sherlock settled himself into his favored thinking pose, letting Rosie sit on top of his chest. "Now, Watson, what was it you needed to discuss with me?"

Forty-five minutes after his appointment, John trudged wearily up the stairs to his apartment. When he got to the door, he couldn't hear any sounds coming from inside. "This cannot mean anything good," he grumbled. Raising an apprehensive hand, John opened the door and peeked into the room.

He could see Sherlock's curly hair splayed out on the arm of the couch and Rosie talking to him, her tiny hands waving happily as she babbled. "Yes, I couldn't agree more. The mind is full of untapped potential. I knew you were smarter than your father. Oh, John you're here, good. I've added Rosie to our crime solving team. She could easily outsmart Lestrade's officers on their best days. Not that they have any of those, of course."

John paused with his mouth hanging open. "Uh huh. Well, I see you both survived."

"Of course we did. How could you doubt me?" With a secure hold on the little girl, Sherlock sat up and stood to his feet. "We have had a very productive day. Young Watson here has been helping me with the latest case Lestrade has brought us. She solved the case in 4.68 minutes."

"That's my girl," John smiled proudly. He held his hands out and waited for Sherlock to pass his daughter over. "I see you had a good day with Uncle Sherlock."

"Ulah!" Rosie declared, drawing both men's eyes to her.

"Did she just-" Sherlock began, stunned.

"Say her first word," John finished in equal shock. "Rosie, who is that?" asked John, pointing at his roommate.

"Ulah!" John cackled in glee as Sherlock stared wide-eyed at his goddaughter.

"Your name is Rosie's first word, Sherlock!" John crowed. "Good job, Rosie! I'm so proud of you!"

"My name is her first word," Sherlock mumbled, eyes staring blankly forward. "Why did she choose my name? Although, when you consider how many times you shout my name in a 24-hour period, it makes sense that she would hear my name more often than anything else."

"Sherlock?" the doctor interrupted his friend. The detective raised his eyes to meet John's. "Just take it as a compliment. It means Rosie pays attention to you."

"Very well, then. I am honored, Young Watson, that you have chosen my name as your first word."

"Now, if I can only get her to say daddy," John lamented.

"It shall happen when it happens," Sherlock assured his friend. "Now," he raised an eyebrow and aimed a smirk at John, "about those experiments..."

A/N: I wish to thank my lovely sister for the story idea. It was also her idea to add Rosie to Sherlock and John's team. Thank you, prison buddy! Please leave a review. I love positive feedback. Thanks for reading!