You used to go to the library, and you noticed that quite often you were alone with a man with glasses. He usually looked very focused and looking for something specific, his face was always frowning, and he clearly didn't come here to rest. On one of those days, he dropped a stack of books not far from you, and you bent down to help, but he stopped you.

No need to.

he said distantly, still in his thoughts, and his face was just as serious.