I think the question of whether it is too sad or not will depend on whether or not you leave it here. Now that you have mentioned the little autistic boy, it has piqued my interest. It would be the cutest, most adorable and awesome fic ever if somehow Sam and Henry, against all odds, managed to get through to each other. The brain is a funny thing. It could happen. You definitely have this propensity to write fics that should be verses...no pressure...:D