Kenny enjoyed playing with Rufus because he didn't have to worry about his dinosaurs being stolen like they were when he played with LJ Jones. Kids on the bus started making fun of Rufus and Cody for not having many clothes to wear, and when Kenny joined in laughing, Rufus stopped talking to him.
You did not provide possible answers, however, the story ideas that are usually found in gothic writing are darkness, madness, supernatural occurrences such as ghosts, dark castles, torture, brooding, decay, and similar. If any fit then that's your answer.