Two infants are Switched at Birth, and a normal middle-class couple, Linda (Darlanne Fluegel) and Peter Pratman (Martin Neufeld), unknowingly find themselves raising the biological son of a violent, insane criminal. The boy, Adam (Matthew Dupuis), is diagnosed with autism, and at age four he shows little responsiveness aside from a talent for art. But he also displays an unnerving preoccupation with violence, and it isn't long before anyone who does anything to offend him starts turning up dead.
Relative Fear contains examples of:
- And Starring: "And M. Emmet Walsh" and later "introducing "Matthew Dupuis."
- As Himself: Chubby the dog is credited this way.
- Better Manhandle the Murder Weapon: Peter, who is completely innocent, is seen trying to remove a screwdriver from a victim's back. He's quickly arrested.
- The Bully: Manny, an older boy who takes piano lessons from Linda, force-feeds Adam dirt, then tells Linda, "I kept telling him not to put that dirt in his mouth, but he wouldn't listen!" Naturally, he's found shot in the head while playing with Adam. His death is deemed to be an accident caused by playing with his father's gun.
- Buried Alive: The fate of poor Chubby.
- The Cavalry Arrives Late: Detective Dennison and several police cars arrive seconds after Adam shoots Gary.
- Creepy Child: Adam's face is mostly blank, except when he narrows his eyes creepily at people who've pissed him off. He also loves watching the true crime channel National Murder Network, which broadcasts graphic details and gory reenactments of recent murders, despite Linda's attempts to ban it from the house.
- Cry into Chest: Linda cries into Peter's chest after some of the murders.
- Daddy DNA Test: Linda eventually signs Adam up for one.
- Dead Person Impersonation: Adam's therapist Clive is really his biological father, Gary Madison, who murdered the real Clive and left his body in a swamp.
- Dies Wide Open: After Earl's life-support equipment is disconnected, he thrashes around a bit before falling on the floor and dying with his eyes staring at the ceiling.
- Enfant Terrible: As a baby, Adam scratches his mother's face.
- Evil-Detecting Dog: Earl's dog Chubby, who barks at Adam every time he's in the room. Although Chubby is really reacting to the presence of Gary hiding in the attic.
- Faint in Shock: Linda collapses after she finds the housekeeper Margaret's corpse.
- Faking the Dead: Gary was believed to have died in a fire, but he was really living under a different identity.
- Flashback Effects: Linda's flashback to Adam's infancy is in monochrome, with echoey sound.
- Freeze-Frame Ending: The movie ends with a freeze-frame of Adam pointing a stick shaped like a gun at Henry and saying, "Bang, you're dead."
- Furniture Blockade: Linda barricades herself with Adam in the attic, pushing furniture over the trap door and pushing a chair under the doorknob of the main door. It only lasts a few seconds before Gary kicks down the door.
- Groin Attack: Linda does this to Gary Madison before she runs into the attic.
- Make It Look Like an Accident: All the murders. Machinery malfunction, dumbwaiter failure, marbles on the stairs...
- Naughty Birdwatching: Linda's father Earl (M. Emmet Walsh) uses the telescope he gets for his birthday to spy on female joggers.
- Nightmare Fuel Coloring Book: Adam's book is filled with surprisingly good drawings of the grisly murders he sees on TV, and later the murders that occur around him. He's actually trying to warn Linda by showing her what the real killer has done.
- Not Blood Siblings: Adam's biological parents were foster siblings.Connie: He could have been my brother. But he didn't want to be my brother. He said I was the prettiest thing he ever saw. I was just a kid then, I didn't know anything! I was thirteen and wide-eyed!
- Old Cop, Young Cop: The plain-spoken Detective Atwater has graying hair and is Properly Paranoid about the deaths, but Entertainingly Wrong about the culprit. His partner, detective Dennison, is a younger, friendlier man who gets excited at being in a newspaper photo (albeit blurry and in the background) and is inclined to write off the deaths as accidents due to feeling there are no logical suspects.
- Orphanage of Love: Linda's real son is being kept in an orphanage with a decent facility that resembles a normal school, and an administrator who shows genuine concern for him despite his supposed relation to a Serial Killer.
- Parents Know Their Children: This is discussed when Linda gets Adam's DNA tested due to her correct suspicions he was Switched at Birth.Linda: I love Adam, but Dr. Hoyer, virtually from the day I gave birth I had this feeling that he wasn't mine. That he didn't belong to me, that he didn't come out of me.
- Perma-Stubble: Detective Dennison is always unshaven, but doesn't have a beard or mustache.
- Scatterbrained Senior: During his birthday party, Earl addresses Linda as "Katie," the name of his dead wife.
- Screaming Birth: Adam's mother screams nonstop for almost the entire opening scene, in contrast to Linda's more peaceful birth. Most of this is rage at the fact that her baby is going to be taken away, but at least some of it seems to be actual pain.
- Secret Squatter: Gary Madison works with the Pratmans as the therapist Clive, while secretly living in their attic.
- Serial Killer: Adam's biological parents, Gary and Connie Madison, are confirmed to have tortured 16 people to death, although they claim to have killed more than 40.
- Soft Glass: When Adam shoots Gary, he flies backward and crashes dramatically through the attic window.
- Spiteful Spit: Adam's mother spits on a doctor for taking her baby away.
- Staircase Tumble: Detective Atwater slips on marbles while running downstairs, falls to the bottom, and is knocked out, leaving him unable to defend himself against the murderer.
- Time Skip: After the opening scene, the movie skips ahead four years.
- Title In: "Four Years Later"
