|“||Andrew, you're not alone up here. I'm here with you! I should've been with you all along, but I'm here now. We can stop this right now, you and me. Andrew, we can just fly away, we can get out of here. We can be family! Andrew? Andrew, look at yourself. This isn't who you are!||„|
|~ Matt Garetty to a fallen Andrew Detmer|
Matt Garetty is the deuteragonist, turned true main protagonist in the movie Chronicle. He started as the secondary protagonist, but replaced his cousin, Andrew Detmer (original main protagonist turned true main antagonist), in the role of the movie as he turned to darker purposes.
Matt is Andrew's more popular cousin. They were close as kids, but they separated in the high school, due to Matt joining the popular crowd, while Andrew remained a socially withdrawn outcast, which caused Matt to cut ties with Andrew to avoid the social stigmas that had already begun to follow his quiet, withdrawn cousin, disliking Andrew because of him being anti-social, not fitting in with the popular crowd, and not attending parties. By high school, Matt drove Andrew around, as his cousin couldn't afford his own car, and was friendly and accommodating towards him, but their relationship was strained and Matt continued to avoid Andrew in public.
Matt invites Andrew to a party to help him meet people, but abandons him in order to spent more time with Casey Letter, of whom he shows a love interest. Later on, Matt befriends popular student Steve Montgomery and, after the party, they find a hole on the ground that emits strange noise. Steve invites a socially inept Andrew, who was being attacked for filming a girl dancing and found crying, to film everything. They found Matt standing outside the hole, which radiates some bizarre, loud vibrations, shocking the three boys and sending Matt, Steve, and a reluctant Andrew to go down the hole to investigate. As Matt, Steve, and Andrew go down the hole they discover a large, blue, glowing crystal object that amuses Matt and Steve, but freaks Andrew out. It surprisingly turns red and begins to generate a radioactive force that pins down Matt to the wall, gives Steve nose bleeds and cuts Andrew's camera off.
Having safely emerged, Matt, Steve, and Andrew come to realize that they have telekinetic powers, and experiment playfully with them by throwing softballs back and forth, building lego structures to dramatic music themes, and skipping rocks. They realize that their powers are like muscle tissue, wherein if they exercise it regularly and gently push it, they're capable of becoming stronger. This is proven when the boys go from barely being able to hold up a softball to managing to move an entire car. All of their experiments are relatively harmless and playful, until one rainy evening, after being out with Steve and Matt all day playing tricks on people in toy stores and teaching each other how to build barriers against physical attacks (they do this by attempting to stab one another in the hand with a fork in a diner), a truck begins tailgating them on the way back. Annoyed, Andrew uses his powers on the truck and ends up knocking it off the road, and sending it sailing into a body of water below.
Shocked and horrified, Matt and Steve race down below to save the driver as Andrew apologizes, saying it was an accident. Andrew attempts to telekinetically pull the truck out of the water but Matt stops him, telling him to "stop doing things." Andrew and Matt wait in distress as Steve jumps in the water and rescues the driver, who they are all relieved to see is alive. Matt starts to call the cops, but Andrew tries to stop him, protesting that the man is fine and that they should just leave. However, Matt doesn't pay attention to his cousin and the three had to stay behind while they waited for the cops. Steve and Matt later confront Andrew about jab the man into the hospital. Matt assumes position as group leader by setting ground rules for the trio in order to avoid another incident like the one on the road--the major one being that they could not use their powers on living things.
The problem eventually resolved, the boys become close again, teaching one another how to use their telekinesis to lift themselves off the ground and fly (eventually becoming so good that they are capable of just hanging around and tossing a football back and forth thousands of feet in the air). They talk about flying around the world together after graduation, with Andrew wanting to go Tibet for its peaceful scenery. Matt eventually agrees.
Steve persuades Andrew to participate in a talent contest with him for school, where he uses his telekinetic powers and passes them off as very impressive magic tricks, causing Andrew in becoming, for at least several hours, one of the most popular kids in school. Matt expresses his confidence that Andrew's social status will be different from now on and that they will be like brothers, even jokingly telling him that he loves him. However, at a post-contest party, after a bad sexual incident with a girl named Monica, Andrew is once again shamed and publicly humiliated, causing in Matt once again avoiding Andrew in public.
One moment, Matt's nose begin to bleed, and he felt Andrew's pain, but is too busy having sex with Casey to pay attention to his cousin's agony, while Steve was accidentally killed by a lightning telekinetically moved by Andrew. At Steve's funeral, Matt confronts Andrew about his death, and is shocked and disgusted to realize that he's still filming everything. When Matt tries to force an explanation out of Andrew, Andrew escapes the situation by flying away.
Matt then finds out about Andrew using telekinesis to rip several teeth right out a bully's mouth, causing him to confront him about this, nearly punching him in the face, but Andrew proves that he is the stronger of the two by deflecting the strike. He tells Matt he won't break his stupid rules and to stay out of his life, and Matt leaves.
While attending Casey's relatives party, Matt's nose begin to bleed and he senses Andrew's agony. He decides this time not to ignore it and discovers on the news that Andrew is in trouble. Matt drives Casey's car to head to the hospital, where he discovers that Andrew is trying to kill his father, Richard Detmer, by dropping him from the air. However, Matt interferes and saves Detmer's life. Andrew confronts Matt about his interference, only for Matt to tell Andrew that this is not a game and pleading him to stop hurting people. Andrew eventually refuses and accuses Matt of "treating him like shit" and that was never there for him. Matt tries to reason with Andrew by admitting that he wasn't always there for him, but that they could put an end to this together, fly away and be a family. When Matt tells Andrew that this is not who he is, he proceeds to outright declare himself an "apex predator", and hits Matt with a bus. The two cousins begin their violent showdown in the middle of downtown Seattle, with Matt still trying to stop Andrew from hurting people.
However, badly injured from both the convenience store fire and the physical confrontation between himself and Matt, and weakened with grief over his mother, Andrew hits the ground twice. Both times Matt attempts to protect him from the police officers threatening to shoot and kill him. When he lands beneath a statue, the police ignores Matt's pleas and Andrew's cry to "leave him alone" and opens fire on Andrew. Andrew freezes the bullets mid-air and drops them to the ground before sending the entire force and all their cars sprawling back with another burst of telekinetic energy in retaliation. He then releases a scream of agony, and proceeds to mindlessly destroy everything around him, breaking all the windows of the buildings surrounding him. Realizing that Andrew can't be stopped or reasoned with, Matt pleads desperately with him for the last time, crying, "Don't make me do it!".
Realizing that Andrew can't be stopped or reasoned with, Matt eventually, painfully relents, and impales his cousin with the spear of a statue. Andrew dies, and Matt flies away before the police can reach him.
At the end of the film, Matt flies away from Seattle with Andrew's camera. When he reaches Tibet, Matt sets Andrew's camera up in front of a small cluster of snowy, Tibetan temples. He tells him that he's sorry for what he did, that he doesn't believe Andrew was ever a bad person, that he loves him, and that he's going to find out what happened to them. The film closes with Matt leaving the camera recording the tranquil image of the temples, and the hope that Andrew has finally found the peace he'd been searching for.
- Andrew Detmer: Matt's cousin. Andrew is an arrogant, self-hating, abused and socially withdrawn outcast, who lives with his alcoholic father, Richard, and his terminally ill mother, Karen. Although Andrew alleges that they were close as children, they have a very strained relationship throughout a majority of the film, with Matt deliberately avoiding Andrew in public, and later admitting that he hadn't always "liked" Andrew due to his difficult nature. Despite how cruel and dismissive he may seem, Matt does sincerely care for Andrew, and risks his life to protect him during the climax of the film.
- Steve Montgomery - Matt's friend. Steve is a charismatic, sociable, and good-natured wannabe-politician. Due to Steve's sociable nature, Matt shows to have a better relationship and a closer friendship with him that with Andrew. Matt has more things in common with Steve, apart from their different relationship with Andrew. Though Matt does not show grief at Steve's death and funeral, being more focused on confronting Andrew about how it happened, at the end of the movie, Matt shows that he liked Steve and that he's going to find out what happened to them, for both Andrew and Steve.
- Casey Letter - Matt's girlfriend. He is shown to have feelings for her when he mets her at the barn party, then again when he tries to show her that he is different from other guys and at first she rejects his flattery. As the movie progresses, she becomes his girlfriend and appears several times through the film. Before the end of the movie, Matt saves her life when Andrew attempts to kill her by taking control of her car at the Space Needles.
- Matt replaces Andrew as the main protagonist of the movie when his cousin turns antagonistic