"Leo didn't exactly explain it in scientific terms," said Lavoisier, coolly returning her human's glare. "She likened it to putting a muddy hand into clean water; the mud contaminates the water, yet the hand only receives the sensation of being wet."

"That's a ridiculous analogy."

Lavoisier shrugged. "That's what she said."

"So because I physically held John's daemon, he felt you? My daemon?"

"In essence yes; but he only felt your soul as it pertained to him. He didn't get any notion of your emotions regarding -"

"I don't have emotions regarding anything else." Sherlock snapped.

"No. Those are just the emotions you hide better than your ones about John."

Sherlock waved his arm exasperatedly as he went back to tying up his shoes. "All these deep and unnecessary insights into my psyche are dull, Lavoisier. If we could get back to the issue at hand."

Lavoisier stood up on the bedcovers. "I think they are absolutely necessary. You've spent your life building up walls, constructing a mask to hide every glimpse of feeling you've ever had, and the second John Watson appeared everything started to crack. Now you've gone and put your hand on his daemon, absolutely destroying every remaining defence, and if you think for one second that I'm going to let you try and block him out again, I question your intelligence."

"But how can I not put up the mask? That's what I do, and I have very good reasons for it, and you know every single one."

"They're not good enough now. Not for John and Leo."

Sherlock ran his fingers through his hair and flopped back on the bed. "Without the mask I am nothing."

Lavoisier rolled her eyes.

"It is my strength." Sherlock continued. "Emotions bounce off me, allowing my brain to run untarnished; a well maintained machine."

"Except they don't bounce off. And if your shield is breached, you have nothing left to protect yourself with. It's a weakness." Lavoisier stalked over the bed towards her human. "You should try and be more like John."

Sherlock grimaced, and spat with disgust, "You would prefer me to be one of the masses, with an average, dull-"

"Don't insult him," Lavoisier snarled.

Sherlock rolled over on the bed, facing determinedly away from his daemon with hunched shoulders. "Caring is not an advantage." He muttered.

"I agree that not caring would, objectively speaking, be a better position. But you do care, and reverting back to not caring is not an option."

Sherlock turned back to face her. "I could try. If I built a special room in my mind palace-"

"Can you honestly imagine yourself not caring about John?"

Sherlock swallowed visibly, staring blankly at the bedroom ceiling. "No," he said softly, voice tinged with wonder.

Lavoisier padded over the bedcover and sat alongside him, her tail resting against his knee. Sherlock slowly reached a hand towards her and rubbed the soft fur along her cheek.

"What did you mean by 'be more like John?'" he asked her.

"John has no shields; he shows very openly what he feels. Ordinary people get a surface reading of him very easily – that's how he hides. People see what they expect to see, so they don't probe any further. So their conclusions about him are inevitably wrong. He hides his true self with white noise – and he's so damnably loyal that anything he believes in, he trusts in it so fully that it makes up the foundation of his character. It's unbreakable."

"When he shot the cabbie," said Sherlock. "His strong moral code."

"Precisely. He's embraced his morality fully, and as such he never second guesses his actions. That is an enviable power, and only one aspect of his strengths."

"He hides in plain sight, whereas I stand out, and thus paint a target on my back."

"Yes; but also, you're like an oyster – once the shell is breached, you're vulnerable and defenceless. But John is the opposite; his defences are on the inside, like-"

"-an avocado?" Sherlock said, smirking.

"You understand my meaning though? And why John's method isn't weak?"

"Obviously. But I don't know how to do it. Or even if I can."

Lavoisier poked the bed with her paw. "I don't know either."

A silence stretched between them.

"I don't think I can." Said Sherlock eventually. "Everything you just explained about John – ridiculously expressive and loyal to the core - that's the embodiment of a dog. He is a dog. Well; wolf – an undomesticated dog. Look at you – I'm a cat. I observe everything and consider myself above it; we're fundamentally different."

"Perhaps we can start with John; he and Leo are the only things we care about, yes? So we discard the mask around them."

"But-"

"Sherlock, they already know how we feel, and yet they're staying; we could not have a safer environment to test this."

"So basically, go back to how things were before except don't close up around John. But why?"

"Because you want to! Of course you want someone to see the true you, the real you, the you I see every day – and now John has, and he still cares about you. Do you want to talk to him about it?"

Sherlock rubbed his eyes. "No. Do you?"

Lavoisier looked at the floor. "No. That conversation would be ... terrifying. But as your daemon, I feel I should advise you consider it."

"The prospect of initiating such a conversation is repugnant. If John knows everything - he would have to do the asking."

Lavoisier nodded, though unenthusiastically; her shoulders slumped slightly. "But I'm glad you listen to me."

Sherlock smiled and rubbed the back of her neck. "You're the only one I ever will."

"Bit arrogant," she muttered, arching into his fingers, "since I am you."

"I like that your form is of a wild animal. I couldn't bear the idea that we were domesticated."

"Sherlock," his daemon said, laughing, "If there's anything you, me, and John and Leo are not, it's domesticated."