Possibly, I'm Insane

“And here is another one for your collection,” Sherlock announced extravagantly.

When John was a baseball player, he did indeed have an extensive collection of things with sentimental value, and those were things like baseballs, gloves, bats.

But now that he had this new life in London with Sherlock, when Sherlock announced there was another one for his collection, it was now apt to be a particularly gruesome and perplexing murder.

John said, “I don’t think I like to say that I collect murders…”

Sherlock said, “No, you collect intriguing and problematic puzzles. That’s how you ended up with me.”