their "wanting different things". Additional characters, introduced in season 4 Arthur Mitchell John Lithgow Arthur Mitchell is the main antagonist of the fourth season. He is an unassuming suburbanite man who has been living a double life as one of America's most prolific and deadly serial killers, dubbed the Trinity Killer by FBI agent Frank Lundy. Christine Hill Courtney Ford Christine Hill was a Miami Tribune reporter who meets Joey Quinn at the scene of Lisa Bell's murder. She starts a relationship with Quinn, often seducing classified police information out of him, including the Vacation Shootings, and the return of Frank Lundy to Miami. The police use her to help catch the Vacation Murderers. It turns out that Christine is the daughter of Arthur Mitchell/Trinity, and is also the shooter of Frank Lundy and Debra. She also reveals that she saw Arthur commit one of his first murders, and she shot Lundy to prevent Arthur's arrest. The police find out the biological connection and arrest her. She did not confess, however, until Mitchell angrily tells her that he wishes she had never been born. Devastated, Hill calls Debra to her apartment and confesses to killing Lundy, begging for forgiveness, but an enraged Debra sobs at the news and then snarls that she will never forgive Hill and that Hill will rot in jail for the rest of her unloved, unwanted life. A completely broken Hill then pulls out a gun as Debra calls in officers to arrest her, and as Debra turns around, Hill sticks the gun into her mouth and shoots herself. Elliot Larson Rick Peters Elliot becomes the neighbor of Dexter and Rita, after they move next door following their wedding. Recently having separated from his wife, Kate (portrayed by Marisa Petroro), he's now a single father, and becomes friends with the Morgans, much to Dexter's annoyance. Elliot eventually develops a romantic interest in Rita. During Thanksgiving he shares a kiss with her, as witnessed by Masuka. When Dexter eventually finds out, he responds with knocking Elliot down. After Rita's death, he is interviewed as a potential witness and suspect, but is cleared. When Dexter is packing up his house, Elliot apologizes to him for kissing Rita. Later, he meets Lumen Pierce while she is staying at Dexter and Rita's now-unoccupied house. Sally Mitchell Julia Campbell Sally Mitchell is married to Arthur Mitchell and is the mother of