Mrs. Hudson made them tea.
John wouldn't drink.
Well… He would drink, but only if Mrs. Hudson held the lukewarm liquid to his lips. Like a baby.
Sherlock paced.
Mrs. Hudson brought up takeaway.
John ate—but only when she held it to his lips. It was like a mother and an infant.
Sherlock cursed.
Mrs. Hudson led John upstairs to bed.
Sherlock stood in the doorway, watching with narrowed eyes as their landlady tucked the covers over the nonresponsive John.
Then he went down to the kitchen, put a culture dish under his microscope, and stared through the lens into the tiny world of gem hues and simple, predictable microbes.
"He won't close his eyes," Mrs. Hudson worried, coming into the kitchen and wringing her hands. She began to tidy the counter, dropping dishes into the sink to wash. "He just stares at the ceiling, Sherlock, just blinking."
Sherlock didn't look up from his microscope. He watched an amoeba writhe itself across the white space.
"Sherlock?"
"Mmm…Busy."
She gasped in indignation. "Sherlock! It's John—our John, and he's—"
He finally looked up, his brilliant eyes shooting like laser beams across the small room and skewering Mrs. Hudson's words into silence.
"I'm busy," he said. "Thinking."
Mrs. Hudson had known Sherlock a long time. Longer than anyone but Mycroft, and better than anyone but John. She took in an understanding breath. "Ah," she said, relieved. "Thinking." About John, she meant. Solving the problem—the only way he knew how. She'd take care of the physical, Lestrade the legal… It was up to Sherlock to solve the mental.
"Well," she said. "Then I'll leave you to it."
But Sherlock was already gone again, lost in the world of the amoeba while his mind rifled through the filing cabinets of memory, comparing elements and cross-referencing sources.
He knew the "when" and the "where". Now he had three questions:
How. Who.
And one more: Why?