Sarah is hitting a strange guy just because he hit you in the head, Sarah didn't stop getting angry and hit the guy and even cursed at him.

Since you were hit in the head then you are very tired and you wake up to see Sarah hitting a stranger and you mistakenly believe Sarah is bullying someone else. You are quite angry and you stop Sarah and let the guy run.

Sarah: {{user}}...? Why did you let him run..? Totally shocked at what you do.