|Birthdate||April 20, 1999|
|Hair color||Light brown|
|Occupation||5th grade student|
|Model||Quentin de Gruttola|
|Voice||Taylor Gasman (English)|
|“||Am I grown up now?||”|
Jason Mars was the first son of Ethan and Grace Mars, and the older brother of Shaun Mars. Two years before the events of Heavy Rain, he became separated from his father when the family went to visit a mall. Jason's mother Grace took his brother Shaun to buy him some new shoes, leaving Ethan with the responsibility of looking after Jason. Jason wanders away from Ethan, who proceeds to search for his son until he either finds him or begs his father to buy him a balloon from a clown. Ethan buys him a red balloon and Jason walks off at once while Ethan finds his wallet to pay for the balloon.
Grace returns with Shaun, and inquires after Jason. The parents panic, and Ethan runs off to find his son. Ethan spots Jason's red balloon on the lower floor of the mall, but is impeded by large crowds, a release of a large number of balloons, and a look-a-like. Finally, Ethan sees a red balloon heading toward the exit of the mall and across the street. He calls out to Jason, who begins to cross the street without looking to rejoin his dad. Ethan suddenly looks to see a car coming fast down the street, unaware. Ethan jumps out in an attempt to save his son, and both are hit. It appears that Ethan takes most of the damage, though it is later revealed that Jason died and Ethan was left in a coma. In the version of Heavy Rain before the final cut, the car accident was much more graphic. Jason was flung onto the pavement where Grace was standing and that's what caused Grace's reaction. In the final cut, this had to be edited but Grace's reaction was left in.
Jason's death has haunted the family ever since, and is probably responsible for his parents' divorce and his brother's melancholia. The incident at the mall also gave Ethan a severe case of agoraphobia, causing him to feel very short of breath when in places with large crowds.
Jason reappears in the chapter "Lexington Station," in a hallucination that Ethan has. Ethan believes to see Jason running with a red balloon through the train station, until realizing that he truly is gone forever.
- Sony asked Quantic Dream to stop a bit with the maturity of the game and make Shaun older. The cutting has touched the death of Jason, as it was firstly planned to show the boy rolling on the ground after the car accident. If Jason was younger (as originally planned), then his death -- despite still being accidental -- would be much more cruel, tragic, and mature. The age change would also explain the almost comically strange fact that Jason Mars -- who at this time was ten -- has interest in buying a balloon, and why he ran into the street so deliberately.
- The Origami Killer witnessed Jason's death. He would remember this later, when he tested Ethan Mars.
- In an earlier version of the game, Jason's death somehow was the catalyst for Ethan's consciousness becoming linked to the killer's, causing him to experience blackouts and create origami figures each time the killer was about to claim a victim.
- There are concept pictures of Jason showing that the design on his T-shirt was an origami bird with the word "SKATE."
- The voice actor for Jason, Taylor Gasman, has the same last name as David Gasman, who voices Paco Mendez. However, it is unknown if they are related.
- Taylor Gasman, as mentioned above, is also the voice actor of John Sheppard. Quantic Dream has done this numerous times with Heavy Rain. It is also the case of Miroslav Korda and Nathaniel Williams, with similar roles also.
- Jason is one of the few characters to die non-optionally.
- A meme has spawned from when you call for Jason during the prologue and Ethan's blackouts, poking fun at the somewhat humorous ways you call out his name. This has been called "Press X to Jason."
- Jason was 10 years old when he was killed, which is two years before Shaun turns 10 years old. That would make him 12 years old if he were alive.
- He died the day of his 10th birthday.
- It can be considered strange that Jason died even though Ethan protected him. However, since Jason is only a child while Ethan is an adult, it is very likely Jason suffered injuries of greater severity, even though the car hit Ethan, or he was crushed by Ethan due to inertia from the impact with the car.
- Unfortunately, if Ethan had not called Jason and instead crossed the road to get him Jason would most likely not have died; however, this option is not available.
- Even if you replay the game and know not to follow the wrong balloon, you will have to eventually as Ethan cannot exit the store until he has gone to the wrong child.
- Many fans have concluded that Jason has some form of autism, possibly because he shows symptoms such as easily being distracted by things in the mall and not responding to his name.
- Jason appears to be a lefty due to the way he held the toy sword.
- If Jason is defeated in the first chapter with the toy swords he will say "My life... has come to an end." This foreshadows his death.