The Boys viewers have a new season 4 fan theory after episode 5's release on Prime Video, and I think they're right

Joe Kessler interacts with Billy Butcher in a dark room in The Boys season 4
Well now, wouldn't this be a diabolical turn up for the books? (Image credit: Jasper Savage/Prime Video)

Full spoilers follow for The Boys seasons 3 and 4.

The Boys season 4 is barrelling towards its conclusion, but Prime Video viewers think they've already worked out one of its most shocking (potentially, anyway) reveals.

With the release of this season's fifth episode – titled 'Beware the Jabberwock, My Son' – we've only got three more entries to enjoy before The Boys departs our screens again. But, while its fourth season has got plenty of loose plot threads to wrap up (or keep dangling in front of us before The Boys' already confirmed fifth season arrives), audiences think they've solved one big mystery involving Billy Butcher.

This is your final warning: full spoilers follow for season 4 episode 5. Oh, and potentially big spoilers for the show's ending, based on the fan theory I'll discuss, are also incoming.

Who – or what – is Billy Butcher's long-time friend Joe Kessler?

Joe Kessler smiles as he greets Billy Butcher in The Boys season 4 episode 1

Who is Joe Kessler really? (Image credit: Prime Video)

Ever since his introduction in season 4 episode 1, Jeffrey Dean Morgan's Joe Kessler has been the source of much speculation among The Boys' TV fanbase. Indeed, the only things we know about him are that he's a current CIA case officer, and that he fought in the War on Terror in the early 2000s. It's during that multi-year conflict that Kessler and Billy Butcher first crossed paths; the pair becoming bosom buddies due to their shared experiences and cruel sense of humor.

That's the extent of Kessler's background we're privy to, so it's understandable that the enigmatic character has piqued viewers' interest. Where did he come from? Why are we only just learning about him now? And how is it that Billy is the only individual who actually interacts with him?

It's that last question that's the most important concerning a big new fan theory about the duo. Kessler has been present where other individuals are, such as the CIA's bustling headquarters, a public park, and at the end of episode 5 when it's revealed that Butcher and Kessler have not only kidnapped Victoria Neuman's partner – the scientist Sameer Shah – to create more of the Supe-killing virus, but have also cut off his right leg to stop him from escaping. 

And yet, Kessler never interacts with anyone other than Butcher. What gives? And why did Sameer look at Butcher in a weird way when Butcher was talking to Kessler in episode 5's final scene? Some fans think they have the answer: Kessler is a figment of Butcher's imagination.

The battle for Billy's soul

A screengrab of The Boys season 4 poster showing Billy Butcher with his head bowed

The party's nearly over, Billy (Image credit: Prime Video)

Given the above evidence, this fan theory, in my opinion, has plenty of weight behind it – so much so that I actually think it's true. It's a hypothesis that becomes even harder to argue against when you're reminded that Butcher is terminally ill. Remember, he shot himself up with that experimental Temp-V serum in The Boys season 3, which is life-threatening with prolonged usage.

As we learned in The Boys season 3 finale, Butcher only has 12 to 18 months left to live due to the Temp-V-created cancerous tumors that have spread throughout his body. Not only that, but, as Homelander (thanks to his X-Ray vision) noted in the season 4 premiere, Butcher also has a congealed black mass of tumors surrounding his brain. It wouldn't be a surprise, then, if said cancerous growths (and those disgusting worms living inside his head) are causing him to hallucinate and see people who aren't there.

As the above X/Twitter post also reminds us, Butcher already has previous form for seeing things – or, rather, people, such as his dead wife Becca, who he's regularly talked to in season 4. Kessler, who's likely dead as well (otherwise, why would Butcher be seeing him?) could be another figment of his imagination, playing the role of the devil on his shoulder to juxtapose the angelic role Becca is fulfilling.

It seems I'm not the only one buying into this particular fan theory. On Reddit, users including yeetTheRhee, ebhanking, and Nobodyherem8 are just three others in agreement with their X/Twitter counterparts over this possible subplot. Over on ResetEra, HeartlessNobody1234 concurred with the prevailing hypothesis.

This season's final three episodes – ones I didn't discuss as part of my spoiler-free review of The Boys season 4 – are being primed, then, to be a battle for Billy's soul. 

Will he listen to Becca (his good side) and use what little time he has left to try and rescue Ryan from the maniacal Homelander's clutches? Or will Kessler (the evil within) win the day, leading Butcher to walk a self-destructive path, try and kill Homelander, and risk turning Ryan (Homelander and Becca's son, don't forget) into Homelander 2.0? We'll find out at some point in one of the best Prime Video shows' next three chapters.

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