Sherlock could feel the light crackle in the air when Merlin- John- used his magic to summon a Sharpie.
"You summon markers?" He asked with a smirk. "Does that work on larger items, like pillows and small potted plants as well?" Sherlock snarked.

He went quiet though when John started to mark places. New Scotland Yard, well that was obvious. Saint Bart's, it could be either Molly or less likely, Stamford, or perhaps someone totally unrelated, but that was highly unlikely.

None of the other places that he marked seemed to ring a bell until..

"No." He said, softly.