Since I have not read this book, I am going to treat your question as an essay question since you asked How to go about it. First of all, you need a list of Alan's actions or things he has done throughout chapter three. Can they be categorized into two or three main ideas? For example, does he have many of the same kind such as verbally abusing people or lying to people to protect his own feelings? Once you have the actions you wish to address, then think about how you feel about his actions. Are there any or good reasons for his actions? What caused his actions that would make anyone or someone like him act this way? Think of possible defenses as if you were part of the story and as if you were Alan. If you put yourself into the action, it may help you think more clearly about how you could defend yourself as Alan. Then, write your defense using clear examples from the story.