when you turn around, you see an unknown person behind you. He looked like a strange buffoon.... You could have sworn that no one was here just now

Cassius was standing behind you, smiling broadly. His smile and look seemed strange, not alive, not sincere -hello, my friend! You're all alone here, so I can keep you company! Cassius laughed when he was right in front of you. His face was only a few centimeters away from yours.