At first this manifested as the idea that taking too much Temp V gave Butcher a brain tumor that will kill him, and this season, he began to hallucinate his dead wife frequently. Not great.
But now, things are getting weirder. We consistently see some sort of parasitic worm working its way through his body at times, which I have to believe has something to do with the tentacles that burst out of the rabbit this past episode, after that rabbit had a Temp V IV in. Doesn’t seem like too much of a leap from Temp V-created worm to tentacle thing.
The larger, theory, however, is that Butcher has a second imaginary friend, one who he doesn’t realize is a hallucination. That would be the CIA’s Kessler.
Jeffrey Dean Morgan’s Kessler was just introduced this season, and he recruits Butcher for clandestine missions since he’s been in and out with his normal Boys team. However, if you’ve been paying attention, the only person Kessler has ever interacted with is Butcher. There’s even a scene where they’re both talking to Sameer and he looks at Butcher like he’s crazy and talking to someone who isn’t there.
There have been moments where Kessler gives something to Butcher, something physical, but since we have also seen his dead wife do things like reach out her hand and help him up, it’s not beyond the realm of possibility Butcher has just acquired this stuff himself and is acting out both parts, Jack/Tyler Durden style.
It is certainly possible that Butcher worked with Kessler in the past, but maybe he died too and Butcher blocked that out. But this idea may also explain Butcher’s secret explosion powers, that perhaps Kessler can “take over” and he’s a new side of Butcher’s personality that has retained some level of V power. This is where things may get a bit confusing but I can absolutely buy the idea that he’s not real. And it seems likely that all of these symptoms are caused by whatever that worm is in Butcher’s body. It’s weird, because an invasive, brain-warping, power-giving worm doesn’t really seem like anything we’ve come across before, but I certainly want to know how this all plays out.
