The hedgehog freaking died.
They'd only had it two weeks. The sad thing was, Sherlock actually held up his half of the bargain. John the Second never went without food, water, attention, and the occasionally thrown (and ignored) stick. Somehow—John the First wasn't quite sure how—Sherlock never lost interest in the thing. Instead of waking John up in the middle of the night to share some case finding or play a new violin piece, Sherlock simply turned to his new pet. Win-win.
But now it was dead, and not of natural causes. John killed it. Accidentally, of course, but that wouldn't make it any easier to explain. John the Second escaped from his cage somehow and, soon after, John the First's foot found him.
When it first happened, John cursed at himself for a good twelve minutes before cleaning up the, er, mess, and trying to figure out how to break the news to an already emotionally unstable detective.
He didn't get much time. Within half an hour, Sherlock burst through the door. "It was the brother, John!" He threw a bag of mushrooms into John's lap and paced around the flat. "I should have seen it earlier. Stupid. The blanket was fleece, so he must have been the killer. Obviously. I phoned Lestrade and, sure enough, they found the weapon in his house. Can you believe it?" He put out his hands, waiting for the routine wow-that's-fantastic-Sherlock bit John the human always offered, but none came. Instead, John kept his gaze on his twitchy thumbs, nodding along to everything absentmindedly. Sherlock's face fell as his deductions worked themselves out. "What did you do?"
John would have normally asked how Sherlock could have known, but right now it didn't matter. "Listen, Sherlock, sit down."
He stood taller and put his arms behind his back. "What happened?" His eyes searched the room for clues, noticing a moved notepad, a half-finished cup of tea, and—finally—an empty cage. Eyebrows raised and eyes enflamed; he turned his gaze to John. "You didn't."
"Sherlock, I—"
"How could you get rid of him? I did what you asked, didn't I?" John thought he noticed a tear forming but he wasn't sure. "He wasn't bothering you. What did he do wrong? Tell me. What did I do wrong? What store did you send him to? Who'll eat the mushrooms? We're getting him back." He threw on his coat and threw John's toward him. "Come on. Lead the way."
John rubbed his temple, filled with guilt and pity, and motioned towards the chair closest to him. "Sherlock, I didn't take him to a shop. Sit."
The odd thing was that Sherlock couldn't deduce when the outcome was personally devastating. Or, more accurately, he could—he simply chose, subconsciously, to block the answer. So with no clue as to what was going on, he sat, waiting for an explanation.
John bit his lip. "Sherlock…I'm really sorry to tell you this, but…" He paused, considering lying as he had lied about Irene's death (who was alive, but he didn't know it, though Sherlock did…well, the whole thing was complicated, but either way Sherlock was—John could tell—heartbroken at her absence). "Actually…yeah. I took him away. I'm sorry. I didn't like him."
Sherlock stared at John for a moment before standing and walking closer. "You're lying."
"What?"
"You're lying. I can tell."
"There's no way—"
Sherlock raised his eyebrows in a don't-you-even-know-me sort of way, but they soon turned stoic. "Tell the truth."
Did he know about the Irene lie, then? John pushed away the thought. "He died. Sherlock. He died."
The detective's muscles sort of fell; at least, that's the only way John could describe it. His entire body went limp, though he remained standing for a good minute before falling into his chair. He stared at some point past John. "Did…I mean…was it his diet? I tried to balance it, but—"
"No. No, it was nothing you did. The cage, uh…it unlocked. Somehow. I must have, I guess. But I was walking around this morning, you know, getting ready, and…um…" He lifted his foot and set it down firmly.
"You killed him?"
"It was an accident, Sherlock, I swear. I never would have, you know, done that. Honest. I'm so, so sorry. We'll buy a new one. Yes? We can go now, if you'd like. Or maybe you'd like another pet? Dog? Ferret? Anything you want?"
Sherlock fixed his shirt collar and cleared his throat. "I'm not a child, John. You should have just said so." He walked towards his room before turning back. "No more pets." Despite all attempts, his voice cracked. "Alright?"
John nodded his agreement as the detective retreated to bed. He sighed, glad that the worst part was over (even though the next few weeks were sure to be rough). Leaning back, he shut his eyes for less than a minute before hearing a door click.
He looked up to find Sherlock's face two inches from his own. "Lock!" was all he got out as his soldier's arm obeyed instinct and brought a fit perfectly to Sherlock's nose. Both boys screamed, one out of pain and the other of horror.
"Don't do that!" John hissed, bending down to check the injury. Probably broken. Lestrade's officers would be laughing for weeks, and Mrs. Hudson's cracks about their "domestics" would come more frequently. "You scared me half to death, you idiot," he growled, gently touching the bridge of the nose.
Sherlock winced and pushed his hand away. "Learn to pay attention to your surroundings, then."
"My eyes were closed!"
"Your ears were open, weren't they?" Sherlock flung his body on the floor, defeated.
John grabbed several paper towels from the kitchen and threw them on the detective. "What did you want, anyway?"
"Oh." He tended to his nose for a few minutes, apparently contemplative. "I don't think a ferret would work. Another hedgehog would suffice. Is John the third too posh, you think, or fitting?"
"You just said you didn't want another—"
"Well what other choice do I have? Before you came along, I was able to figure things out on my own. Now I've developed this weakness: I'm sharper when you're in the room. My best work happens at night, as you're aware. You've clear signs of sleep deprivation. John the second worked well enough as a replacement, but you've gone off and killed him. Unless you'd like to return to our original arrangement, we'd best head to the shop."
John cleared his throat, fruitlessly trying to hide his sensitivity. "The hedgehog was a good replacement?"
"Oh don't be like that. You replaced my skull, remember?" Sherlock sighed and looked at the empty cage sadly. "I must admit, you've been the top contender. The skull attracts attention, and the hedgehog wasn't very stimulating."
"Stimulating?"
"Well how am I to know how smart it is? When you're helping me, you ask idiotic questions. That helps to remind me that the criminals were, most likely, idiots, and I need to think like them. Pets don't help in that way, do they? They just sit there. Conversation has its usefulness, I suppose."
John rolled his eyes at the insult but was brimming inside at the compliment (he knew there was one in there). 221B never got another pet; the two can be seen, nearly every night, talking about the latest scandal in London. And neither one minds at all.