Sherlock had been slightly more unusual lately, which was saying a lot. After coming out of Soo Lin Yao's apartment, he'd been distant, raspy, and... well if John was reading him correctly, paler than usual. Not his skin (seemingly impossible), but his colours. Like he'd almost drifted away.
John had asked him, concerned, whether he was alright. Sherlock, being himself, only waved a hand at him and claimed he was fine.
John didn't quite believe him, but what was he supposed to do.
Oh Sherlock, you say you're fine, but your aura is looking paler around the edges and it's looking a bit saggy around the head and shoulders area. So I'm going to ask you again- are you fine?
No, that wouldn't do at all.
Soo Lin, when they finally met her, shocked John. Not her personality, she was perfectly pleasant, average intelligence, pretty. No, it was her aura, her colours that scared John. Because while she was shrouded in a dark grey, hiding, near her skin was angry fiery red and orange. She looked like she was burning. It frightened John.
But as she told them her story, she calmed somewhat, looking less like she was burning, and looked more like she was glowing. But then they heard her brother. Her brother who came to kill her. Gone was the fire, gone was the glow, and the dark grey threatened to meld into a black and envelope her completely. She was terrified.
(John would have been interested to know, that as she spoke to him right before he killed her, her aura calmed completely and mellowed to a pale green. Then there was nothing else.)
He watched Sherlock as he realized she was dead. Shame flickered in at his edges. Was it shame? Sherlock didn't seem like the type of person who would feel shame. Yet there it was, dark blue slipping in at the edges, a clear sign of guilt or shame. John would know; he'd seen it so often. Even in himself.
But they solved the case. Not entirely, Sherlock was unhappy with the conclusion, but John and Sarah survived, and that was good enough for them.
Still, dark blue lingered in Sherlock for the next week before it faded away completely.