This story is pretty basic... Split screening the life of the kid and a dog that has been abandoned and lives on the street. The Kid is on his way to School and Kids never approach him and because of his disability. On that same day he gets bullied by some seniors.. at that same time the stray dog comes to rescue the kid from the bullies and saves the kid.
Another story that came to my mind is the concept of a Kid being mentally challenged or have Autism and doesn't talk to anyone but his Imaginary friend. There is a dog who is lonely without love and finds this Kid and tries to befriend him but gets pushed away by the Kid. At last they unite and the dog becomes to best friend.