Julian Albans is one truly nasty piece of work. A thoroughly unpleasant young man, he routinely subjects Auggie to cruel jokes and insults concerning his facial abnormalities. One of his favorite jokes is to liken Auggie to Darth Sidious, a character from one of the Star Wars movies who gets his face burned by Sith lightning and becomes seriously deformed as a consequence.
If one wants to know why Julian has turned out to be such a revolting excuse for a human being, we need look no further than his mother. For once we're introduced to the character of Mrs. Albans, we're left in no doubt that, in the case of Julian, the apple hasn't fallen very far from the tree.
Julian's mom is kind of a big deal on the school board—a vice president, no less. And she's used her position to push for a review into Auggie's application to Beecher Prep. Apparently, she's unhappy at Beecher's becoming an inclusion school, a place where “normal” kids are mixed in with special needs students. As she regards Auggie as a special needs student, she doesn't want him at Beecher Prep.
In actual fact, however, Auggie isn't a special needs student at all, and so there's no justification for his being excluded. It seems to be the case that Julian's mom just doesn't like the look of Auggie's face, in both literal and metaphorical terms. She clearly harbors an ugly prejudice against Auggie on the basis of his facial abnormalities. Evidence for this comes in her Photoshopping Auggie's face out of the class picture.
When all is said and done, the sad fact is that this unspeakable woman, mother to an equally unspeakable son, is riddled with prejudice.