How do I write such a character in a novel?
Hi, I actually just want to know how my character might react to something like this. What might he say? What would a person in such a situation say?
He's the character who starts screaming and getting angry because he's being left out all the time.
So he doesn't notice what the others are planning and only realizes it afterwards, which makes him angry.
You already described him: He gets angry at every little thing and screams. Let him do this in your novel and you’ve described him well.
This is your own thing