John walked through the door of 221b to see Sherlock sitting in his chair, just as John had left him this morning. There were no body parts on the table, and none in the refrigerator. After seeing that the flat was no messier than it had been before he left, John came to the conclusion that Sherlock had not moved from that position since he had left to go to his practice that morning.
John walked into the kitchen and put the kettle to boil. He walked back into the sitting room to see that Sherlock still had yet to move a muscle. He was still holding his violin, just as he had been this morning. His eyes stared out into the air, focused on something seen only by him.
"I'm making some tea, you want any?" John asked.
"Hmm..." Sherlock hummed. John took that as a yes. John walked back into the kitchen and prepared each of them a cuppa. He reached out to hand the cuppa to Sherlock, but Sherlock made no move to take it. After holding it out for a few seconds, John sighed and set the cup on the table beside him.
"What are you doing?" John asked. He didn't expect any answer, and nor did he get one. At least, not until five minutes later.
"Thinking." Sherlock muttered.
"You've been doing that an awful lot lately." John commented, looking up from his mug. It was a moment before Sherlock answered.
"Stop trying to deduce me." Sherlock said. "You're making yourself look like a fool. Just ask me what I'm thinking." John stared at Sherlock for a second, wondering how in the world Sherlock had figured out exactly what John was thinking, then shook his head, deciding that it didn't really matter. Sherlock was Sherlock. John sometimes wondered if even Sherlock himself knew exactly how he knew what he knew. Then again, he probably did. Sherlock was Sherlock after all.
John cleared his throat. "So... uh- what are you thinking then? Something interesting?"
"Yes, very." Sherlock said, "A paradox... Listen closely, you maybe of some help." John nodded. Sherlock sat silent for a moment.
"I'm listening." John prompted.
"If a person was to have two choices, one being they could help a lot of good people, but to do that they have to harm some bad people people, or, they can not harm bad people, but it will turn out not good over all for the good people. Which is the right choice?" John thought for a moment.
"Well, I suppose that would depend on just how much good it would do." He said.
"Quite a lot more than it would hurt." Sherlock said. "But helping lots of people in this particular way would not be encouraged by most. In fact, most would see it as counter-productive."
"But it's not?" John said. Sherlock nodded. "Then I suppose I would do that." John said. Sherlock nodded thoughtfully for a moment then stood up abruptly. "Alright." Sherlock said, "Let's go."
"What?" John said, his mind still processing Sherlock's sudden movement. Then it caught up. John immediately stood up and grabbed his coat. "Where are we going?"
"To the prison." Sherlock said.
"Why?" John asked, obviously confused.
"To break Moriarty out."