they don't see him how i see him

“Kaaacchan~~! Guess what!” Katsuki froze in place, and slowly turned to face Izuku, who had come up behind him on the sidewalk, silent as a shadow. He watched him, wary, as the short boy’s smile grew wide, too wide. It looked like if it stretched any further, it would tear the corners of his mouth. He looked giddy, and covered his mouth with his hands, like he was hiding something. Katsuki had always known there was something off about Midoriya Izuku, and it scared him. He never had any proof that there was something wrong with the boy, and nobody else ever seemed to see past the sunshine façade he put up.