By Definition
She's over one hundred and fifty years old, of course she's been in love. She's not blind, and contrary to popular belief she has indeed feelings. Rukia has seen it all, the joy, the heartbreak, the magic of the first kiss and the tragedy of the last.
So you can trust her to say it's not that with Ichigo. It's something entirely different.
That's not saying they're not close. She's not dumb, she knows it's uncommon to just move into someone's closet, and that if it happens, it's probably bound to bring people together really close. She's heard the guy talk in his sleep, and she's seen him cry (which by the way she's pretty sure he'd die before letting anyone see). While it's certainly not endearing, she finds it touching, somehow. It makes him human when there is so much about him that's not.
It's a valid argument that his appearance is not so bad. To be honest, she's actually intrigued by his hair, and it especially fascinates her that his eyebrows are of the same colour, whereas his eyelashes seem to be black. As seen from a distance, naturally, and during a fleeting moment, because it's definitely not like she's staring at him out of the blue.
Since you insist, there are in fact times when she feels the urge to touch his head, ruffle the whirl of hair at the back, but that's more like scientific curiosity as she's never seen another boy with that strange hair colour. It's soft, you know. From what she's gathered when she hit him. Repeatedly.
She's not exactly asked for it, but she knows that his lips are rather soft as well. It wasn't what you'd call a proper kiss, seeing as it was freezing outside and she was cold and angry for some no doubt important reason, and if you give her some time, she'll remember it, too. The kiss itself had an Ichigo-like quality to it: He obviously hadn't thought about it, it was quick and rough and she's still a bit surprised at how she managed to feel any softness at all. Later on, his face matched his hair colour and he avoided her eyes at all costs and she knew beyond a doubt that this was the first time he'd ever kissed a girl. And that it scared the hell out of him.
Now even if Rukia is a bitch sometimes – and she likes it that way – you can't really accuse her of being cruel, because she's never ever called him up on it, and she's not planning to, either. Although sometimes, it is really tempting, especially when he's lecturing her or announcing to the world just how incredibly full of himself he is.
It's not just to save his precious dignity that she doesn't talk about it. It's that it means something to her. Not in the way you all think, though.
She's learned that there is something special about the two of them, aside from the life-saving thing that they've brought to perfection. It's like they really know each other: They know when one of them is worried, or in danger, they know when they should talk and, somehow, when they should listen as well (although Ichigo can't keep his mouth shut through it). Mostly to their utter disappointment, they even know when it's for the best just to reject the other's opinions.
When he kissed her, she became aware that he acknowledged their unspoken connection, and probably had done so since the time he'd taken that juice box and opened it for her. It was why he seemed not afraid to leave her in Soul Society, why though he always berates her for disturbing his peace by leaving or returning, he never tells her to stay on one side, and why (after a little prodding) he never refuses to help her with whatever she's doing, even if he thinks of it as "kind of stupid".
He's gone far out of his way to tell her, now that you mention it.
She'll never forget the sudden calmness that seeped through her entire being. She remembers how she looked at him and it occurred to her that he wouldn't do this for anyone else. And that exact feeling has her convinced that this cannot by any means be love. She knows for sure he'll be waiting for her, she knows for sure he'll be coming for her, she knows for sure there'll never be another occupant in his closet – with all the implications you could possibly see in that – and she's learned the hard way and more than once that with love, there's always something you're not sure of. That's why. And you're not going to change her mind about it, since you quite obviously can't mess with a hundred years worth of experience.
However, Rukia has a distinct sense of what's fair. So, when she noticed that Ichigo felt somehow… exposed by the whole incident, she decided on an uncompromising way to tell him that she might have understood what he was hinting at. To get even, if you want to look at it that way.
That's how she's ended up on his bed at exactly four-fifty this morning, with a small tray of breakfast she's spent hours to prepare (actually, she's spent a whole lot of her time on earth secretly watching Yuzu making breakfast to get it right, and it still looks, well, not right). And even if he is a light sleeper, Ichigo sure takes his time waking up.
When she resorts to poking him quite unceremoniously, he lets out a sigh and opens his left eye.
"Hollow?"
She nods. He opens his right eye. "How come you never just visit?"
"Because you never invite me, idiot."
He grunts. After a few minutes he seems to realise that she's sitting on his bed. He looks at her a bit irritated, then tries to get up. His hand brushes across the tray, and he grunts again, in surprise, or so she thinks.
"What's that?"
"What does it look like?"
"You don't really want me to answer that, do you?" He eyes the food suspiciously.
"It's breakfast, you jerk."
"Are you sure? It seems alive to me."
"You have five minutes to find out."
She settles on a look that always promises the worst-case scenario, and maybe he's just tired, because he blinks in defeat and shoves something that has a remote resemblance to something possibly edible into his mouth. Rukia watches with mild interest as his expression changes to one of confirmed suspicions, while the healthy rosy colour of his face turns to green, then to red. She wonders if it's anything to do with the ingredients and is in the middle of blaming his weak stomach when something happens that neither of them expected. He gulps whatever that stuff is down and gruffly remarks "I knew it", and she thinks that this time, he'll get away with it, and then he smiles.
Have you ever seen someone smile against their own free will? Not a grumpy child that's tickled or a pissed off girlfriend you've bought a really expensive gift. More like a boy who hates to smile so much he actually tried to sell the thing in exchange for a permanent scowl, only that nobody wanted it because it made an irritating rusty noise from neglect.
Imagine this really tough smile that fights its way to the surface and refuses to back down until he has to bite his lip to keep it from bursting out of his face and right into hers. Which makes her smile anyway. And maybe it brings the slightest flush to her cheeks. Sure feels like it.
As an afterthought, she'd appreciate it if he learned that there are moments when he should – instead of talking, listening, waiting or coming for her – just try to kiss her again, maybe with more time at his hands. Of course, she won't tell him or something… after all, he's not as experienced and might easily confuse what they have with love. And it's something entirely different.
