Why is Roy so interested in the boy he sees running in Hoot by Carl Hiaasen?

There are several possible reasons why Roy, the main character in Carl Hiaasen's novel Hoot, is interested in the running boy. One of the main reasons is that Roy's interest in the running boy is how Hiaasen advances the plot. Without Roy's interest in the running boy, he wouldn't meet Beatrice Leep or her step-brother Napoleon Leep, also known as Mullet Fingers. If he hadn't met those two, he wouldn't have known about the burrowing owls on the property where the new Mother Paula's restaurant is being built.  
Roy attracts Beatrice's attention when he develops an interest in the running boy and begins asking questions about him, as well as following him. This is how he discovers Mullet Fingers is a runaway. Mullet Fingers vandalizes a construction site because he knows about the burrowing owls and wants to protect them.  
Roy forms a friendship with Mullet Fingers. With Beatrice's help, they uncover the truth: Chuck Muckle and the construction foreman, Curly, hid the environmental impact report. At the groundbreaking ceremony, Roy, Beatrice, and Mullet Fingers tell the town about the owls, prompting Officer Delinko to arrest Chuck Muckle, which stops construction.  
Another reason Roy is so interested in the running boy is that he sees him out of the window of the bus when Dana Matherson is choking him. His interest in this strange boy gives him a distraction from Dana's torments. It also gives him something to focus on, since the move to Florida was not his choice. He loved living in Montana and did not want to leave.  
Another reason the running boy piques Roy's interest is that the boy is breaking the rules, and Roy is a person who follows the rules. Mullet Fingers should be in school, but he ran away from the boarding school he is supposed to attend. When Roy gets involved in saving the owls, he is the one who wants to find a legal way to help them. This contrasts with the methods of vandalism that Mullet Fingers uses.