John has a lightbulb moment.
Lightbulb Moment
"I wouldn't," Sherlock said quietly, his voice suddenly in John's ear. "He's dangerous."
"Criminal mastermind?" muttered John, never removing his glare from Umbrella Man (who, to his annoyance, seemed amused). They'd encountered a few "criminal masterminds", including a cabby and a redheaded crook.
"Close enough," responded Sherlock, stepping past John towards Umbrella Man.
"No need to be so dramatic. I occupy a minor position in the British government."
"Point proven, don't you think?"
John watched them, a strange sense of recognition crossing him. Same stance…same authoritative, charismatic personas…same hint of orangeish in their dark hair…
Oh. Oh, duh.
Prompt was #3: orange