It wasn't even something Kurt's dad had taught him.
No.
It was just the most fundamental instinct of a human being who felt threatened and wanted to get out of that situation.
To charge forward, clench their fist, and deal as much of a massive blow to the enemy's face as they can.
What Kurt didn't expect, however, was that even though his was a clumsy punch, only filled with raw rage, anxiety and past traumas, it landed on Johnny's face like a hammer head, sending the bully several steps backwards in the corridor.
Kurt straightened up and looked at the remaining six individuals.
If he could see himself in the mirror now, he would see his eyes fully bloodshot, his mouth open in a grimace that of a wild animal ready to feast on its prey, and bulging veins protruding from his neck, slowly leveling down with his skin.