I'm not going to help my mentally disabled brother with his video game
Why can't you help your brother out with his game?
Because he is annoying.
You should help out your family when they need help. Just because he is disabled, doesn't mean you should ignore him or not help him.
Never mind I guess I will help him.
I am glad you changed your mind. You're brother will appreciate the lending hand and I am sure you two will have some fun playing together.