Cordelia moved into an apartment where Dennis and his mother, Maude Pearson, once resided. The Angel Investigations team discovered that the apartment was haunted by the spirit of Dennis' mother, Maude.
After some investigation, the gang discovered that Maude Pearson had died of what was believed to be a heart attack on the same day that her son had disappeared. The group came to the conclusion that Dennis had killed his mother in order to be with a woman she didn't approve of. However, after being haunted by the ghost of Maude, Cordelia broke down a wall in her house, revealing the still tied-up body of Dennis Pearson. The team deduced Maude had tied her son up when she learned that he was leaving her to be with his girlfriend, subsequently building a brick wall and trapping him inside, where he suffocated to death. When Cordelia broke down the wall, it unleashed the spirit of Dennis, who destroyed his mother's ghost. Because the ghost of Dennis still inhabited the apartment, and Cordelia refused to move out, Dennis then resided with Cordelia as an invisible, and rather benevolent, roommate. He even prepared a surprise birthday party for her.
At one point, Cordelia stated that the best romantic action she could get at the time was "an invisible ghost who's good with the loofah", hinting at a deeper relationship than just roommates.
Dennis was very attached to Cordelia. A recurring joke was to try to prevent her of the hostility of some invites with bad intentions like Wilson Christopher, Faith Lehane and Harmony Kendall, generally by disrupting a conversation by slamming doors.
Their "living" situation continued until Cordelia ascended to be a higher being. Dennis was not heard from again after "confronting" the gang about taking Cordelia's possessions out of the apartment. He presumably still haunts the apartment.
Dennis usually remained invisible and, unlike his mother, didn't possess a visible human form. However, when he did manifest physically, he took the form of a ghostly face surrounded by tendrils of light.
Behind the Scenes
- He was portrayed by BJ Porter.
- In a possible reference to Star Wars Episode I: The Phantom Menace, he was occasionally referred to as "phantom Dennis."
- He also appeared in the opening credits.