That's probably reducing the effectiveness of this good (albeit dated) family melodrama from director Michael Apted. An early role from Robert Downey Jr. (his Melba Toast one-liner is memorable and classic dry Downey Jr.), Peter Weller, who at the time was best known as the likeable offbeat hero Buckaroo Banzai. And the debut of the less annoying of the two Coreys (Haim).
In Firstborn, Weller plays Sam, a leech of a character who charms his way into the life of Wendy, a recent divorcee with two high school sons and desperate to find a new man to fill the role of stepdad. Wendy is played by Teri Garr, coming off two highly successful comedies (Tootsie and Mr. Mom) and apparently eager to show her dramatic chops. She does a good job, too...the proud mother of an honor roll student and his much less mature (and not just because of his age) kid brother.
Sam floats in and is aloof at first with the two sons Jake and Brian. Then he tries to win their affection by grilling out with the family (cooking with Mesquite!), tossing a baseball around with them, and buying them unexpected ritzy gifts like a moped for Jake. Sam talks about opening a restaurant too. Where is his money coming from?
Jake senses something is off with the guy. As more is revealed about Sam's shadiness, Jake starts faltering in school, failing tests and getting into heated arguments with his teachers. Even his friendships with Iron Man and Carrie Bradshaw (another early career role in the movie - Sarah Jessica Parker) turn sour. Jake then discovers Sam's source of income and the movie turns into a domestic thriller.
This movie was the first produced by Sherry Lansing at Paramount. The finale involves a fight in a suburban home that foretells a future movie she would produce with Michael Douglas and Glenn Close. Even little Brian (Corey Haim) comes to the rescue with a bat.
Out of all of the actors, the most memorable performances have to be from Christopher Collet, as Jake, and Weller, as the shady and eventually dangerous Sam. Collet would later star in the underrated sci fi comedy "The Manhattan Project," and then apparently drop off the face of the Earth. Weller became RoboCop.
Garr is effective and if she seems weak in the film, it's because her character initially is weak. Even Haim is quite good as the little brother, and would appear two years later in the underrated high school romance "Lucas" before teaming up with the other Corey for his skyrocketing popularity, and eventual downfall.
This is a decent drama that plays a bit like a TV movie, but with the success of "Ordinary People" and other early '80s dramas focused on American families, made it to the box office for a very brief run. It later became a sleeper hit on video.
