Kevin is a hero in some very distinct ways. One clear way in which Kevin is a hero is that he saves Max. It is Kevin who risks his own life to save the life of his friend. When Max is in trouble and is in the process of being strangled by his father, Kevin is the one who comes to his rescue. He squirts Killer Kane with his water gun and transcends his physical limitations. Kevin stands up against the embodiment of evil. In defeating the force of darkness, Kevin is a hero. At the moment where he demonstrates heroism in the most demonstrative manner, Kevin has risen above all. He embodies the knight who saves those in distress in the way he rescues Max. In saving Max, Kevin is a hero.
Kevin is also a hero in that he recognizes the need for self- sacrifice. Kevin understands his own mortality. He understands it in a painfully evident way. Kevin knows he is going to die and nothing can save him. Just as his body will never grow, Kevin knows that his time is coming to an end. In a very heroic manner, Kevin compels Max to write down their adventures. Through this suggestion, Kevin is heroic. He understands that the true heroes are ones who can be remembered even after they have passed. Kevin understands that his own life can serve others in the form of hearing about the legend of the "quests." Kevin pledges himself to something more than himself. In asking Max to write the story of "Freak the Mighty," Kevin demonstrates heroism.
In a more subtle way, I would suggest that Kevin is a hero because he never surrenders his belief in how life should be as opposed to how it is. A critical definition of heroism is this capacity for transformation. The inspired hero sees what is and is able to transform it into what can or should be. Kevin does this. He understands that his own physical capacity is limiting. His heart and mind are active agents of change, even when his physicality lacks it. In his love for robotics and Arthurian legend, Kevin embraces this transformative quality. This ability to envision what can be from what is defines his heroism in characterization. It is in this way where Kevin is a hero in how he views the world and his place in it.