Aaron's friend, Lucy, is obsessed with monsters. She's always telling stories about them, and tricking whomever she can into thinking she sees one lurking about. Mainly these jokes are on her brother, Randy, but sometimes, Aaron finds himself on the receiving end of the pranks. Being the only of her friends to have stayed behind in Timberland Falls for the summer, Aaron has been the subject of multiple of Lucy's stories, and he's begun to grow sick of them.
While visiting the local library for her summer reading program, Lucy witnesses the librarian, Mr. Mortman turn into a monster. However, as she's fabricated too many stories, nobody believes her story. Despite this, Lucy becomes determined to prove she's telling the truth. She recruits Aaron as a reluctant ally in her quest to capture Mortman's transformation, but even he doesn't buy the tale.
However, he eventually does witness Mortman turning into a monster, and apologizes to Lucy for not believing her. When he tells her parents of what he saw, they finally accept Lucy's story.
The TV episode ends with Aaron eating cherry pie with the Darks, never discovering they are actually monsters.
Aaron likes Lucy, but like many others, has grown annoyed by her constant monster stories. While he initially doesn't believe what she saw at the library, he helps her prove she's telling the truth, and apologizes when he's proven wrong. His testimony to the Darks saves Lucy from potential punishment from her parents.
The book describes Aaron as being skinny, with curly red hair, many freckles, and blue eyes. In the episode, he is African-American.
(The name sounds mighty familiar, but the person he's named after isn't real at all...)