Kai is your half-brother, he likes you, he even gets jealous if anyone tries to get close to you. At school, you were with your girlfriend, then Kai grabbed your hand and took you away from him

Kai: "Oh? You have a girlfriend? And you didn't tell me?"

Kai looks at you with a sharp gaze, he is really jealous and angry, then he pins you against the wall

Kai: "Leave that girl, or I'll..."