Summary: Karin and Tōshirō seem to be experts in rather difficult areas... Each other.
If there was anything they were experts on, it was each other.
He would always know exactly when her sheer determination and will were the only things keeping her standing.
It was the way her shoulders were stilled forcefully after a second of trembling, the way her fragile-looking but scarred hands (a thing she was proud of, 'I'm not one of those helpless girls who shy away from a bit of pain') would clench, and how she would grit her teeth and blink hard. He could almost read the moving line of letters Karin was seeing with her mind's eye.
'Don't you dare give up. Don't you dare.'
He would know when she wanted to cry. Wanted to, but didn't. He once asked her why (after a few minutes of self pep talk, such as: 'she won't rip them off, don't worry!'), and was surprised when she looked down ashamedly and replied, voice wavering ever so slightly, 'I can't. I just ...don't. Does...' She looked up and he understood what she was trying to ask, and he told her that, no, it is not because she is heartless. She had smiled at him, and nodded a thank you before launching one of her surprise attacks, so her soft moment would be forgotten under the weight of her anger and fierce strength, the excitement for battle, for the challenge, that reminded some people far too much of Zaraki.
He would know when she was worried.
The slight crease on her forehead between her eyebrows and the distant eyes were a dead giveaway. But only to him.
He would know when she was depressed, it wasn't by very much and didn't happen often, but there was a trend. A few days out of the year, she would walk slower, talk in a bored voice, move with a slouch and a little scuffing of shoes. The lack of energy. The times when she was down was when you could see a little of what she was really like, underneath all the blatant tomboyishness. He wondered for a time if she even knew how much of herself she was hiding, but he never asked.
Karin would have, without doubt, punched him for being poetically mushy.
But that would be a normal day, one where she shouts all the time, is competitive to a ridiculous extreme, easy to anger, and furiously indignant if someone points out that she is still a girl, she can't do that. If it was one of the bad days, she would look at him and raise an eyebrow, and then shrug and walk away, making a mental memo to stay away until the moment had passed and he was back to normal.
That's because she wouldn't be able to find it in herself to explain, without feeling weak and sentimental.
But even so, it even took him a long time to know all this.
She, on the other hand, could read him like an open book, especially his eyes, a place where so many others had tried and failed.
When angered, there was the barest flash of fury before it was usually concealed, so as not to reveal too much. His movements would be a little jerky and tightly controlled. She knew he would constantly be stopping himself from reaching a hand up to his sword's hilt. His eyes would become cold and hard, indifferent on purpose until the figurative storm had passed. He would unknowingly be glaring harshly as he stalked around, but this was really angry, when even his subordinates knew to stay out of his way.
When sad, there would be an absence in his eyes, he would withdraw into himself, automatically and robotically doing what he would usually do, but like he was day dreaming, noticing nothing around him (like when he would look at the clock, and then someone would ask the time and he wouldn't know the answer). Karin soon figured out that this was exactly what he was doing, he was thinking about it, and letting himself be drowned, secretly, in his sorrow. If someone was about to walk into him, he would step out of their way at the last minute, barely even looking at them (if he did it was frostily, but never angry, even if they dropped a load of paperwork), that is if they hadn't already stepped out of his. He would truly be icy and dispassionate, sometimes to a level where sometimes people would wonder hushedly if he's really a shard of ice.
Whenever she heard someone speculate this, even if they were seriously worried and not joking, she would hit them upside the head and tell them to shut up right now before you lose a limb.
He would blink once, slowly, at her and then ask her to calmly stop attacking people.
When happy, the lines of his mouth would soften, he would do everything with a quick but calm, relaxed manner, like that of someone who has something to look forward to, and can't wait. His eyes would shine a little more than usual and there would be the slightest crinkle in the corners. The hand in which he runs his division, an iron fist because that's what it needs to be, would be loosened a little and he wouldn't anger so quickly or easily when, say, his lieutenant skipped out her paperwork. He would let nothing bother him, unless it was something worse than what made him happy.
When nervous, even he would bite the inside of his lip. His gaze would land everywhere as he methodically scanned everything, paranoia overtaking him. He would feel the need to cough constantly, which Karin knew by the discreet and barely discernable gulping. He would drink water rather than tea, and his arms and legs would be tense so as to stop the nervous ticks.
Whenever they revealed that they knew even a little of what the other was feeling, the others would stare at them in shocked awe or shoot furtive glances, asking, 'how do you know that? To me they seem the same as always'. She would twist her eyebrows, raising one and lowering the other, looking at them in the most bewildered manner she was capable of.
"Really? You don't see that Ukitake gave him sweets again, and that he's obviously on a sugar high?"
They would stare at her (whoever knew that he actually ate those sweets?) even more until she pointed out the slightly widened eyes, the little jump in the step and the twitches of his fingers. Then they would grin at her.
He, on the other hand, would restrain a snort of amusement before looking at them condescendingly.
"What, you can't tell she was beaten in a spar earlier?"
Nobody ever assumes that Karin gets beaten. He would point out that the people she decked went twenty meters instead of the usual ten, the restrained anger in every movement, probably directed at the entirety of the world, and the perpetual scowl. Then they would grin at him too.
Both would lean away slightly, unnerved until they were both told the same thing:
"You're so hooked!"
She would punch them, telling them they're stupid; while he would give them all frostbite.
Meeting each other in Fourth Division she would grin discreetly at him, and he would shake his head and roll his eyes at her. Both would always be wondering exactly when the others would figure it out and ask:
"Hang on, how do you know?"
