An interesting Back to the Future theory explains the subtle changes in Marty McFly's personality over the course of the trilogy by inferring that traveling to the past affects his own upbringing. First starting in 1985, Back to the Future remains one of the most beloved sci-fi movies of all time, thanks largely to its easily accessible take on time travel. Followed by Back to the Future Part II and Back to the Future Part III to round out the trilogy, the story of Marty McFly and Doc Brown's time-traveling adventures remain an iconic staple of the sci-fi genre.
Over the course of the trilogy, Marty McFly undergoes significant character development. He starts the first film as a little more than a carefree teenager, but after his adventures in Back to the Future's time-traveling DeLorean, he becomes a more well-rounded and reasonable person. The franchise paints this character development as the inevitable result of Marty's adventures through time, with him learning valuable lessons from the existential dread that goes along with his timeline hopping.
However, one why Marty Mcfly hates being called a chicken, but it also goes a long way towards explaining other subtle changes in his character throughout the trilogy.
Marty Changes George McFly's Life In Back To The Future
The events of Back to the Future stem from Marty accidentally time traveling to 1955, where he inadvertently prevents his parents from meeting. The film's plot centers around Marty righting that wrong before he ceases to exist, which sees him intervene in the young lives of his parents in order to ensure his own existence further down the line. The central premise of Marty jeopardizing his very existence and attempting to fend off the resulting paradox is what secured Back to the Future's lasting success.
Upon successfully introducing his parents and returning to 1985, Marty realizes that his circumstances have changed considerably. At the end of Back to the Future, Marty McFly's father, George, is an entirely different man from the one that Marty knew before traveling to 1955. This is due to Marty's actions in the past profoundly affecting George, prompting him to be more confident and assertive, standing up to his childhood bully and securing himself the career he dreamed of as a teenager.
Marty Is Later Unable To Back Down From A Challenge
Though Marty seems to his original upbringing, the changes to his family's lives have a huge effect on him. Not only does Marty's home life notably improve, but in Back to the Future Part II, it's revealed that there's an issue in Marty's future. There, it's revealed that the inability to back down when called a chicken has destroyed Marty's dreams, and his children are acting out of control. Marty in Back to the Future Part II is shown to be reasonably similar to George McFly in the original timeline: a man who failed to live up to his potential due to one particular character flaw.
This is where the theory comes in, as it posits that the more confident George McFly was a very different parent from that of the original timeline. This would have affected Marty's own childhood, making him more self-confident, perhaps explaining why he refuses to back down from a challenge as a point of pride. In addition, Marty specifically asks his parents to "go easy on him" if he ever burns their rug; though it's a throwaway moment, it hints that Back to the Future's Marty McFly might have been raised differently as a result. If Marty's childhood lacked the same boundaries and consequences that it originally had, it only follows that his character's persona would shift slightly to be less conscious of the consequences of his actions, resulting in his refusal to ignore a challenge later, ruining his life.
The Back To The Future Sequels Change Marty McFly
It's not just the events of Back to the Future that seem to prompt changes in Marty McFly. Back to the Future Part II sees other changes to the timeline, most notably when Biff Taffen travels back in time to make himself rich. This results in Marty returning to an alternate 1985 in which George McFly is dead and Biff is his rich stepfather. This seems to subtly affect Marty's behavior, too - while Biff's life improved, Marty's didn't, and he acts somewhat recklessly in this timeline, even going as far as to jump from the roof of a skyscraper to escape Biff.
Back to the Future Part III perhaps evidences the biggest shift in Marty's character, however. Traveling back to 1885 to rescue Doc Brown, Marty not only meets his own ancestors but is yet again challenged, and yet again, he accepts. After facing a life-threatening duel as a result of his refusal to ignore a challenge, Marty only narrowly avoids death, manages to save Doc Brown, and returns to 1985. It's here that Marty es his final test: he turns down the challenge to partake in a street race.
Though this could be down to Marty McFly's character development, the theory paints this change in a different light. By traveling into his family's distant past, Marty once again changes the present. This is confirmed by changes to 1985's Hill Valley upon his return, and therefore it's not unreasonable to assume that the change in Marty's character is also a result of his actions in the past. There's no genuine reason for Marty to have changed other than him having learned a difficult lesson, as he has no foreknowledge of the crash that would have awaited him had he accepted the challenge, and therefore, time travel was responsible.
Why Travelling To The Future Doesn't Affect Marty In The Same Way
Throughout the Back to the Future trilogy, Marty McFly and Doc Brown travel back and forth through time repeatedly. However, it only appears to be Marty's trips into the past that affect his character. This is because of the nature of the past as opposed to the present: by affecting his own timeline, Marty's character instantly begins to adapt to his new past, which his own meddling repeatedly alters. Traveling into the future doesn't come with the same complications, as Marty can't affect his own history in quite the same way, and therefore his actions can't change the fundamental nature of his character.
The theory is so utterly convincing as it uses little more than the basic logic of time travel. Back to the Future character is shown to change numerous times over the course of the trilogy, and this simple yet clever theory gives an effective answer as to the nature of that change. Marty McFly's repeated meddling in the past was a key element of Back to the Future, and it would seem that it changed far more for the character than just his circumstances.
