The following post contains SPOILERS for Joker. This is not a joke. It is also not a Joker-style prank. Do not read any further unless you’re prepared for a discussion of some of the film’s biggest plot points.

One of the oldest clichés in adventure stories is the scene where the villain confronts the hero and lays out their motivations for all the nasty stuff they’ve done and, in the process, tries to defend their particular point of view. Invariably, the bad guy ends up drawing parallels between themselves and the good guy, and usually spouts some variation of the line “We’re not so different, you and I...”

The notion of hero and villain appearing as two sides of the same coin has been used time and again in Batman comics in conjunction with many different characters (including the one who provides his own coin to really hammer home the metaphor). The most popular dark mirror image of Batman is Joker, who has been battling the Dark Knight across various artistic medium for almost 80 years. In all those years, though, Joker has never treated quite so literally as an evil double of Batman as he is in Todd Phillips’ Joker, where he is revealed as (possibly [maybe]) Bruce Wayne’s illegitimate brother.

In the film, the Joker — AKA Arthur (Joaquin Phoenix) — learns from his mother Penny (Frances Conroy) that his father is Thomas Wayne, the wealthy businessman running for mayor of Gotham City. As Joker’s mom tells it, she worked for the Wayne family for years, and had a secret relationship with Thomas that resulted in her son, Arthur. Throughout the movie, Penny keeps sending letters to Wayne, who she insists is a “great man” who will help them with their living situation, but she doesn’t explain why. Eventually, Arthur gets so curious he opens one of the letters, which reveals the origins of his parentage.

Warner Bros.

That’s just the first layer of surprise. Arthur investigates his mother’s claim by going to Thomas Wayne’s home, where he briefly meets his “half-brother” Bruce, and is told by Alfred that his mother is a liar. Alfred insists Penny was fired because she was delusional, not because she got pregnant. The trail then leads to Arkham State Hospital, where Arthur finds his mother’s patient file and another twist: His mother isn’t even his biological mother. Instead, she adopted him — and then stood by while he was abused by her boyfriends. Penny’s Arkham file even includes Arthur’s paperwork from an orphanage. This final revelation is treated as the moment that Arthur loses his flimsy grip of sanity, as he murders a former friend (and possibly the neighbor he imagined was his girlfriend), dies his hair green, smears on some clown makeup, and makes his debut on live TV as “The Joker.”

If this plot twist left you in shock, you’re not alone. Even hardcore DC Comics fans won’t see the revelation of Joker’s surprising connection to Bruce Wayne coming, because it has no precedent in the history of Batman comics. Over the last eight decades, Joker has been given a few possible origins, none of them treated as definitive. Very little has even been concretely revealed about his life before the dip into the vat of toxic chemicals that bleached his skin and died his hair. His sadistic acts defy explanation.

Sometimes he’s a scientist turned standup comic. Other times he’s a petty crook named the Red Hood. Whatever the story, he’s rarely is given a real name, although in Tim Burton’s Batman Jack Nicholson’s Joker was also known as “Jack Napier,” and in some subsequent comics, DC’s Joker also answered to Jack. (The alias “Arthur Fleck” is also a Todd Phillips invention.) In none of those stories was the Joker Batman’s brother, so to get back to the question in our headline, if you’re wondering if Batman and the Joker are brothers in comic-book continuity, the answer is no — those two characters are not related (at least genetically).

Warner Bros.

Of course comic-book movies are under no obligation to honor the continuity of their print counterparts — and Phillips left Joker ambiguous enough to leave some room for those who want to argue that Batman and Joker are secret bros to make their case. After Arthur finds all that evidence at Arkham that proves his mother is lying, he discovers a picture of his mother as a young woman, signed with a romantic inscription from one “TW” — Thomas Wayne. If Penny imagined the entire relationship, why did he write her affectionate messages? The Thomas Wayne of Joker is depicted as obscenely wealthy and equally powerful. Penny claims she was sent away to prevent a scandal. If Thomas is as sleazy as he seems to be in the film, doesn’t he have the money and ability to cover up an illegitimate kid? It can’t be that hard to fake adoption papers and have a mistress committed to an asylum in a city as corrupt as Gotham.

On the other hand, by the time Arthur finds that signed picture, his perceptions of reality are probably not to be trusted. He hallucinates an entire relationship with a neighbor (Zazie Beetz), and there are suggestions that other events are figments of his imagination as well. Arthur’s given a gun by a co-worker as an unsolicited, but later he’s told by his boss that the co-worker claimed Arthur asked for the gun. Is the co-worker lying or is that another relationship Arthur imagined? There is a lot of talk on the television about a garbage strike that there doesn’t seem to be a lot of evidence of when Arthur’s walking around Gotham. Did he make that up too?

Arthur is about as unreliable as narrators get, so there really is no definitive answer of whether Batman and Joker are brothers within Joker. His mother could be telling the truth, and Thomas Wayne could be the ultimate power broker and manipulator. His mother could be a mentally ill liar, and Arthur could be an orphan she took in. Or neither scenario could be true and everything Arthur finds in his journey through Gotham City could be delusions of his broken mind.

To the film’s credit, even though Joker appears to give the character the definitive origin he’s always been missing, Phillips offers so many conflicting stories about his ancestry that the man we’re left with is just as opaque as the guy appearing regularly in DC Comics. Ultimately, whether you want to believe Batman and Joker are brothers is in the eye of the beholder. Sort of like whether a joke is funny or not.

Gallery — Our Favorite Joker Easter Eggs and Movie References: