Antagonists do not have to be "evil" (a concept I should say I do not think exists).

An antagonist just has to be against the protagonist.

They might both want the same thing, so they are naturally opponents. Think sporting teams. Your team is the team you want to win, who your are invested in - your protagonist. The opposition wants the same thing and so they stand in your team's way - the antagonist. Are they "bad guys"? Only from your perspective. Their fans have the complete opposite view.

Don't think in terms of "good" and "evil". The world does not work in such black and white terms, so maybe the stories don't need to, either.

In fact, reading your post above, it sounds like the annoying kid might just be on the spectrum in some way.

Good luck!