what is proof that Julain is a antagonist?

Julian Albans is the story's main antagonist: a kid at school who is consistently rude to Auggie, and tries to turn the entire school against Jack when Jack decides to keep being Auggie's friend.

"Why is your hair so long?" Julian said to me. He sounded like he was annoyed.

I didn't know what to say, so I just shrugged.

"Can I ask you a question?" he said.

I shrugged again. Didn't he just ask me a question?

"What's the deal with your face? I mean, were you in a fire or something?

JULIAN WAS FOREVER MEAN TO AUGUST. HE WAS VERY RUDE TO HIM. HE LEFT NOTES IN AUGUT'S LOCKER. PLUS ABOUT PHOTOSHOPPING THE CLASS PHOTO WITHOUT AUGGIE IN THE PHOTOSHOPPED PICTURE