By the end of “The Handoff,” we have an idea of what Thaddeus is turning into and it’s not ghoulification.
His arm falls off right before he, Maximus and the Ghoul fight a bunch of Deathclaws. Earlier in the episode, he shows the Ghoul a mouth with baby fangs growing on his chest. The Ghoul’s horrified reactions to Thaddeus’ transformation makes it clear that whatever is going on is a fate worse than death.
The show blends body horror with humor. Thaddeus is actually cheerful about his “ghoul” status. He even tries to bond with the Ghoul, thinking he’s found a kindred spirit. It’s a sharp contrast with what’s happening to him. It’s what Fallout does best, pairing genuine terrors with dark comedy.
Was Thaddeus Given a Modified Version of FEV?
The inhaler Thaddeus used in Season 1 probably contained an FEV-based substance, the same virus responsible for creating Super Mutants in the Fallout games.
FEV rewrites the host’s genome. Unlike radiation exposure, which causes necrosis in ghouls, FEV triggers rapid cellular mutation. That’s why Thaddeus heals instantly, and feels no pain as shrugs off losing a whole arm. His body is rebuilding itself at the genetic level.
But FEV doesn’t always mutate you into something that’s somewhat functional.
Why He’s Not Becoming a Ghoul
Ghouls lose their noses as their skin deteriorates gradually. They don’t spontaneously lose limbs or grow mouths on their bodies.
Thaddeus’s arm falling off is a sign of unstable cellular reconfiguration. His skin damage looks more like tissue remodeling rather than ghoul necrosis. Also, Ghouls don’t develop new anatomical structures. They lose features instead of gaining new ones.
Is Thaddeus Turning Into a Centaur?
It’s possible that Thaddeus is turning into a different type of mutant: a Centaur.
Centaurs are FEV creatures created by exposing a mix of humans and animals to the virus. The Master made them by dumping dogs, cats, and people into vats filled with FEV. The result was grotesque hybrid monsters. Large, fleshy amalgamations with multiple limbs, heads, and mouths.
Thaddeus’s symptoms match the mutations Centaurs experience better than anything else. Random mouths forming on the body? Check. Limbs detaching as his body reconfigures? Check. Chaotic, unpredictable mutations that don’t follow a consistent pattern? Check.
Super Mutants grow larger and stronger but maintain a humanoid form. Centaurs are body horror incarnate. They’re unstable fusion creatures that bear little resemblance to what they used to be.
Other Possibilities
Some fans wonder if Thaddeus is turning into something similar to Harold from the games. A ghoul-adjacent creature but not a true ghoul. Harold was a unique FEV mutant who retained his intelligence while his body transformed in unusual ways.
Thaddeus could be transforming into a floater instead. Floaters are another FEV creature, though they don’t match Thaddeus’s symptoms.
There’s still a chance he could become a Super Mutant, but the multiple body parts and unstable mutation pattern don’t fit. Super Mutants are engineered soldiers, while Thaddeus’s transformation is too chaotic.
So far, the show hasn’t confirmed if any of these theories are true.
What Happens Next
Thaddeus’s mutation probably isn’t finished. FEV transformations take time, and his current state suggests he’s only partway through the process.
Whether he’s becoming a Centaur, a unique FEV hybrid, or something the creators made specifically for the TV series, one thing is clear: Thaddeus isn’t becoming a ghoul.
Whatever he’s turning into is far worse.
