Up to date with sherlock bbc, this is a follow on so if you haven't seen season 4 look away now as will be full of spoilers. Based 3 months after last episode.
Disclaimer: I do not own sherlock mearly the new character to be introduced and a half eaten bagel.
"Sherlock?" John called up the stairs of 221b baker street. "Sherlock are you home? Molly cancelled on me.." He pushed his way up the stairs carrying a loaded nappy bag with Rosa swinging out from him.
John rounded the top stair to his apartment and heard voices, his step faltered, for only a moment. Mycroft was here. He pushed the door open and smiled. Both Holmes boys stopped their chatter to stare. John hadn't made a habit of bringing Rosamund here but today had to be an exception.
"Molly got called in, i'm already late i need you to watch her Sherlock, please." Before he even had a chance to respond John had plopped her in his lap. "Mrs. Hudson said she will be up to help soon."
"Wha.. No, you can't leave her here.. I.." He stumbled for words.
"My my little brother, he deems you responsible. Hmmphf" Mycroft smirked.
John was halfway out the door, "I will be back by 3 i swear, you know i wouldn't do this unless i had to." And with that John was gone.
"What am i to do with her now?" Sherlock asked no one in particular, "I have things to do!" Rosa sat looking up to her uncle drooling.
"Well Sherlock, I will see you next week, untill then.." He looked down at the little girl on his knee, "Good luck."
As swiftly as Mycroft had arrived he left. Leaving Sherlock along for only the second time with the infant. He paced the living room holding her hoping Mrs. Hudson would arrive soon, he needed to get to scotland yard, Lestrade was waiting on him.