choose a character that notices a positive change in Max in the book Freak the Mighty

Gram sees this. Gram is Max's grandmother, who he also lives with. She is a very polite and courteous woman, balancing out Grim's more serious one. She takes good care of Max, and when he becomes friends with Kevin, she is very happy that he has made a good friend.

Gram, because she thinks he has saved Freak/Kevin's life