I have an affinity for frustrated Sherlock. Far too much fun to write.

John worked all morning, so it wasn't until that afternoon that he found out there had been another murder; he actually found out on the walk home, when he opened his phone to find that at some point Sherlock had stolen his number and had texted him quite a lot.

John there's been a murder. SH

Another one, Lestrade says I should clarify. SH

John grinned as he walked to the nearest tube station, earning strange looks from passer-by. He should ask Mycroft to get Lestrade knighted. All the same, he put his phone in his pocket until he got on the tube, pulling it out once he was seated and scrolling through the texts with a few chuckles.

It's another boring person, but there's a cactus left on his back. SH

Why a cactus? SH

Lestrade is looking into cactus-selling stores in London to see if he can find a matching cactus. Idiot. SH

It's brutally efficient; he's killing people but not enjoying it. Why kill them, then? SH

Cactus is from Brockwell Park Community Gardens. Says so on the pot. SH

Why a cactus? It still doesn't make sense. Nothing about this case makes sense, John. SH

It's a Schlumbergera bridgesii. Represents endurance and passion. SH

Who looks at a cactus and thinks, "This looks enduring and passionate!" SH

I bet it's about sex. SH

John you really should check your phone at work. SH

What if you got kidnapped again? An "I'm fine" would suffice. SH

The Greenhouse takes volunteers; we should go. SH

At this point the texts stopped, and John blinked at his phone before replying.

I'm fine. We can go this evening if they're open. You don't have to sign your texts, you know.

-

John walked into the flat to have Sherlock whirl and take him by the shoulders, seating him on the sofa before he had a chance to take off his coat. She slammed the door once he was seated and gave a manic gesture to the coffee table, drawing his attention to the tea sitting there.

"Sit, have your inane drink, I need to think," she ordered, and John raised an eyebrow as she paced the room, hands gesturing as she spoke. All the same, he did take his tea, letting his eyes follow her across the room over the edge of the mug.

"It doesn't make any sense, John, they're all perfectly ordinary, this last one didn't even have porn on his laptop!"

John nearly spit out the tea, but she just continued with a wave.

"Oh don't splutter like that, it's totally normal to look for that sort of thing, but that's my point, these people are too good! There's some other reason for killing them. And I don't understand -"

"Can I get that in writing?" John interrupted. She ignored him.

"- because they're not connected, the banker barely left the bank, the bailiff was constantly at the courts, and this last fellow was constantly at some musical gig or other, there's no reason. It's like they're being chosen for being good, but then what does the cactus have to do with any of it? And why did he break his pattern with the bailiff?" She tugged at her curls angrily, as if the answer was hidden in her head and she could just pull it out.

John shrugged. "Maybe he didn't have to leave anything."

Sherlock whirled. "Yes! No. Wait. Maybe? What could have been there? The bailiff was perfectly ordinary. Dull. Boring."

"And you said I'd be next. Ta for that," John said, raising his cuppa with a frown at Sherlock.

"He wouldn't go after you if he knew you like I do, he only goes after the ones that he knows are boring. Can't put all the boring people in London under protective custody, it'd be the whole city," Sherlock scoffed.

"I thought you just said they're too good? Isn't that unusual?" John asked in confusion.

"Which is just it, he's choosing people that are going to be hard to trace, he's covering his tracks and yet exposing them, he's doing this with all the method and knowledge of a man who doesn't want to get caught, but for no reason. There's no logic to it!"

John leaned back. "So he doesn't want to get caught. Most murderers don't."

Sherlock rolled her eyes with all the authority of the expert. "Not serial killers, John, there's always a flaw, something that points you to them, so they can be recognized for what they are."

"Which is?" John prompted after a moment.

"Geniuses," Sherlock said, and John frowned. She looked at him and made a dismissive gesture. "In their own right, they are; they do manage to do things most human's can't, John."

"Or things most human's don't, not can't, Sherlock, because most people aren't homicidal maniacs," John emphasized, watching his flatmate do a nearly perfect about-face to pace the room again.

"And guilty ones always leave clues; please find me so I stop is subconsciously written in everything they do. This man isn't guilty or prideful, John. It's perfect," she said, ignoring him as her eyes lit up. John groaned. Of course she'd be seeing this as a challenge instead of horrifying.

"So how do we find him?" he asked, and Sherlock groaned, throwing her head back even as her eyes lit up.

"Same as before, with the briefcase. We wait for him to make a mistake."