"What happened to your knuckles?"

"I slammed my fist against my desk while studying"

"Why?"

"I got mad"

"Why?"

"I couldn't get anything into my head"

For once, when he was actually telling the truth, she couldn't believe him. He did get mad and slam his fist down on his study desk because he couldn't think probably. All because he already had thought flooding his crammed mind. Suicidal thoughts.