WARNING: The following contains spoilers for director Todd Phillips' Joker, in theaters now.

Joker makes some serious changes to the history of Gotham City and it's residents. While exploring the origins of the man who would become Joker in a grim and grimy version of Gotham City, the film also introduces a darker and colder version of the Wayne family than had previously been portrayed.

But one of what would appear to be its biggest changes actually has a deep connection with the history of Batman. The revelation that Arthur Fleck might actually be the son of Thomas Wayne hints that on top of being the future Joker, Arthur is also the live-action debut of Thomas Wayne Jr, sometimes known as Owlman.

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BLOODLINES

Joker trailer Arthur Fleck and Bruce Wayne

The film opens with Arthur living with (and caring for) his elderly and infirmed mother, Penny. One of the only things she has the ability to keep her mind on is Thomas Wayne, who is running for Mayor of Gotham City. She formerly worked for him and claims that he was one of the kindest people she ever knew. She's even been sending him letters for years that seemingly go unanswered. Arthur eventually learns, however, why she keeps sending those letters: upon opening one and reading it, Arthur finds out that she apparently had an affair with Thomas when they were younger, which produced a child: Arthur himself.

This alters the trajectory of the story, as his quest for answers takes Arthur across Gotham City and deeper into his madness. He goes to Wayne Manor and confronts Alfred, who denies the connection and claims Penny was mentally ill and obsessed with Thomas. He even reveals that Arthur was actually adopted. This seems to be collaborated by the medical paperwork Arthur steals from Arkham Mental Hospital. His eventual meeting with Thomas doesn't go any better, with Thomas eventually punching him out. But while the film seems to deny that Thomas is biological Arthur's father, there are enough clues left throughout the film (notably a picture of a younger Penny, signed with love by a "T.W.") hinting the connection might be more real than anyone wants to admit.

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THE SECRET WAYNE SON

Bruce Wayne having a secret brother isn't new to Joker. Bruce having a fully grown supervillain brother, Owlman, is a plot point from the alternate realities from both JLA: Earth 2 and the New 52 version of the Crime Syndicate.

Before this, the idea can be traced back to World's Finest #223 by Bob Haney, Dick Dillin and Vince Colletta. Thomas Wayne Jr. was the eldest son of the Wayne family. However, he suffered from major head injuries after being hit by a car in his youth. Becoming mentally unstable, his parents had him committed to the Willowood Asylum. The Waynes hid away Thomas' existence, to the point where Bruce never knew him until well into adulthood. The two brothers came to blows after Thomas had been forced to become the "Boomerang Killer." Following a brief stint with Deadman, Thomas died taking a bullet meant for his brother.

A modern version of the idea appeared in the New 52 in the form of Lincoln March. Created by Scott Snyder and Greg Capullo, March claims he was Thomas Jr. He was apparently Bruce's younger brother, born prematurely due to a failed attempt on Martha's life. Sent to Willowwood Home for Children to recover, the Waynes were murdered shortly after. Thomas was taken in by the Court of Owls, who trained him.

When Bruce returned to Gotham City and threw off their plans to have Thomas take control of the Wayne legacy, they gave him the identity of Lincoln March. Running for Mayor of Gotham City, Lincoln eventually turned on the Owls and confronted Batman, intending to kill his "brother." Bruce later learned that he did indeed have a baby brother, but according to medical records, he died 12 hours after being born. This hints that Lincoln was just conditioned to think he was Bruce's brother by the Court of Owls. Lincoln was a recurring threat for years a few years before being taken out by the Court of Owls.

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WHAT DOES THIS MEAN?

Bruce has had villainous brothers in past stories. But making the Joker into Batman's brother might actually make Joker one of the most tragic versions of Bruce Wayne's origin. It paints the Waynes in an even darker light, suggesting one version of events where Arthur was (at least initially) only hidden away to hide the potential embarrassment of Thomas Wayne having a child with one of his staff. Even if Arthur wasn't his son, Thomas Wayne's visceral reaction to him didn't help his mental state at all.

His quest for answers ends up pushing Fleck further down the road to becoming Joker. His anger at his mother's deception about both Thomas and the apparent adoption leads him to murder her in the hospital. Even more tragic than the possibility that Bruce's eventual greatest enemy is his brother is that the chaos unleashed onto Gotham by Arthur's actions inadvertently leads to the deaths of Thomas and Martha Wayne in an alley.

Fleck may have been responsible for the death of his own father without even realizing it, all the while being cheered on. It's a dark and wild interpretation of the Batman mythos, but not one without a connection to the original comics.

Directed by Todd Phillips, Joker stars Joaquin Phoenix, Robert De Niro, Zazie Beetz, Bill Camp, Frances Conroy, Brett Cullen, Glenn Fleshler, Douglas Hodge, Marc Maron, Josh Pais and Shea Whigham. The film arrives in theaters Oct. 4.

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