The cab was waiting outside, the program started at six, it was already half five, and Mrs. Hudson, forgetting that she had volunteered to babysit for the Watsons, had taken a few herbal soothers too many and was soundly asleep in her sitting room. John bounced his son and paced the entryway to 221B, considering his options.
"I could watch the baby," suggested Sherlock, watching his friend stalk back and forth, rattling off ideas to his tranquil wife like Sherlock wasn't even in attendance.
"Your sister is out of town, but what about our neighbor, that Kelly girl, the one with the nose rings—"
"I said I can watch him."
"I heard you the first time. And the answer is no—absolutely not," John said shortly and then resumed his pacing. "I suppose we could just take him, if we had to—"
As if in protest, the infant's whimpering morphed into a full-out wail. Sherlock cringed at the wrenched screeching, but tried once more to persuade his friend.
"I am perfectly capable of watching a baby for a few hours. People far less intelligent than I do it all the time," the detective said, annoyed at being treated like an impeccable. His tone softened. "Besides, I've missed out on so many landmarks in your son's life. It only seems fair to let me make up for lost time."
Sherlock's best, most sincere gaze was lost on his friend, who refused to even spare him a glance. However, Mary watched the whole exchange with softening eyes.
"John," Mary commanded sweetly, and the doctor stilled. She walked over to her husband and lifted their wailing baby out of his arms, cooing and shushing as she went. The child's cries quickly quieted into sniffles. She turned to Sherlock. "He shouldn't need a changing for another hour or so, and if he starts to cry again, he's probably either hungry or wants a cuddle and bounce. Bed time is at eight, but he can go down earlier if he's fussy. You've got John's mobile number if you have any questions. We should be home before midnight."
She planted one last kiss on her son's tiny brow and then passed him into Sherlock's stiff arms.
John looked at his best friend distrustfully. "I don't know if this is—"
"Come along John. We'll miss dinner." She smiled, took her husband's hand, and led him to the door. He sighed and allowed himself to be pulled along.
"Seriously, Sherlock, if have trouble, any trouble at all, just—"
"Have fun! Goodnight boys," Mary called, shushing the good doctor one last time and whisking him onto the darkening streets of London.
Sherlock stood in his silent flat and stared down at his charge—the infant looking surprisingly comfortable in his inexperienced hold. The detective was happy to note that the little thing had ceased its original squirming and was looking at him with curious, expectant eyes, as if to say, "now what?"
"How would you feel about a bit of undercover work?" Sherlock asked. The baby gurgled in pleasure—most probably from the timbre of the detective's voice—but the genius took it as a yes.
"Excellent."