Chance, The Guardian

Until Chance's 16th birthday he was almost like everyone else, and then he woke up in the dream world. As he learns what this means he learns more about what it means to be him, along with finding a new friend in Jason, someone who once bullied Chance for his Down Syndrome. The two of them work together to defeat a being from another plane, who wants to use the dreamers to help him take the Earth from the humans... and it's not until then they learn there are others in the dream world.