"Such Days Deserved" by Lee Hallison appeared in Daily Science Fiction on June 26, 2013. "It is a magical summer, and some children imagine that a bum found collapsed in an abandoned lot is really an alien in disguise."
I love reading good stories about "that magical summer," and "Such Days" definitely falls into this category. All the necessary elements are there: danger, magic, horror, a moral dilemma, and the inevitable growing up that must occur when summer is at an end. 6 out of 7 rocket-dragons.