From the beginning, Kakashi was scared of Asuka. Because Asuka was braver than him. Not the face-a-squadron-of-enemies-of-unknown-abilities braver, of course, because Kakashi did that all the time. Though he was pretty sure that face-a-squadron-of-children-of-unknown-temperaments was pretty much the same thing, and Asuka could handle that just fine.
It was the other kinds of bravery that Kakashi found so intimidating. Asuka had suffered too, but she didn't hide. She didn't retreat behind a mask, or a book of porn, or nonchalance. She threw herself into her work too, of course, but not as a form of escape. It was because she cared about it.
And that's what was so scary about Kitsune Asuka. She cared. She allowed herself to care. About people, about things, about the village. Didn't she know better by now? When she bought Naruto ramen and ruffled his hair, didn't she realise Naruto would probably get killed on a mission someday? That when she wished the ninja in the mission room success, that might be the last she saw of them? That she sent her students into a world where they would kill or be killed, die fighting for their village or perhaps for betraying it?
Asuka had, of course, been the one to ask him out. Kakashi didn't make first moves. Hell, Kakashi didn't make moves if he could help it. Too risky. Even if it went well. Especially if it went well. Because going well just meant it was going to go more horribly later.
But Asuka had asked him out, and that implied she'd started to care about him. Which Kakashi didn't get, really, but he'd been surprised enough to go along with it. At least at first.
But they went on that date, and somehow that led to another, and sometimes Asuka would just turn and look at him and smile like the world was perfect.
And then he was trapped. Because Asuka did care about him, and it scared him. And he cared about Asuka enough not to want to hurt her. And because hurting her was inevitable, Kakashi was terrified.
Asuka was a chuunin. Didn't she get that trusting Kakashi was a bad idea? That he'd just end up getting fucked up worse than life as a ninja did to you anyhow? But no, Asuka just went on caring about Kakashi as though the past didn't matter. Or the future wasn't bound to happen.
And then...
And then one night, he saw Asuka break down. It must not have been the first time Asuka had done it, but it was the first Kakashi'd seen, the first time he'd seen a tear in the bravery and cheerfulness that Asuka wore like a cloak. Kakashi had come over that evening to find Asuka sitting absolutely still at her table, her face drained of colour and her eyes seeing something that wasn't there. When Asuka had turned to face him, finally noticing his presence after what felt like hours of standing there watching, she'd practically launched herself at Kakashi in a way that would have knocked down a less athletic man.
In between incoherent noises, Kakashi had been able to make out that a team of genin had been killed on a mission. This team consisted of students from the first class Asuka had taught at the academy. They were some of the first students she'd graduated, apparently.
And somewhere in all of that, in spite of the pain of knowing Asuka was hurting and she couldn't stop it, could only try to ease it, something in Kakashi loosened. Because Kakashi knew that Asuka was scared. That Asuka feared caring as much as Kakashi did. That the real bravery of Kitsune Asuka was not that she denied that she could be hurt, but that she knew it, and chose to care anyhow.
So maybe it was okay that Kakashi was scared.
And then Kakashi cried too. Because he cared.