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"Kageyama supposed it should have been obvious the moment they met—the reckless and borderline destructive nature of Hinata's determination.

He dove for the ball like it was the last one he’d ever hit in his whole life, and even when his underclassmen seemed concerned after a particularly nasty fall following a failed receive. Hinata just wanted to stay on the court. In those minutes, though, all Kageyama could see was what was in Hinata’s heart:

The drive to learn and grow and win.

He saw it sparkle in his eyes. In the way he moved. In the way he talked. In the way he cried in front of him after their first game.

And that, Kageyama knew now, was his first mistake: being so completely overwhelmed and blinded by Hinata’s drive that he missed what lay buried underneath it.

He missed the monster it concealed, and what it did to Hinata on and off the court."

Or: Hinata just wants to get better, but he doesn't realize he's hurting himself in the process. The rest of Karasuno does. Trigger warning.