The Fire Devil reveal in Chainsaw Man was every bit as astonishing as it was made out to be. In a Fujimoto-esque fashion, the true host wasn't the one the community had heavily speculated to be. Rather, his identity was a brilliant reference to an event that took place nearly 103 chapters ago in the story.
In a nutshell, it was the brother of the man Denji didn't save when he fought the Cockroach Devil.
Now, a while later, the man had returned to exact revenge on Chainsaw Man, the one individual whom he once adored. But looking closely, such reveals by Fujimoto are rarely ever straightforward, and that looks to be the case presently. The Fire Devil seemingly draws inspiration from a popular Greek myth surrounding the brotherly duo of Prometheus and Epimetheus.
Chainsaw Man: Fire Devil concept finds inspiration in popular Greek Myth
Before diving in, it is worth understanding what this Greek myth refers to. It speaks about two brothers, Prometheus and Epimetheus. After the fall of the Titans, the brothers were tasked by Zeus with the creation and distribution of life on Earth. Epimetheus (meaning 'hindsight/ afterthought') was to assign animals with various qualities, while Prometheus (meaning 'foresight') focused on humans.
But by the time the latter sculpted the humans, he realized that Epimetheus had given all the good qualities to the animals. Feeling that humans had no advantage, Prometheus stole fire from the Gods to give to the humans to enable progress. This act of defiance angered Zeus, who punished Prometheus by chaining him to a rock and having a vulture devour his liver every day, which regrew at night.
Put into the Chainsaw Man narrative, the older sibling can be seen as Epimetheus, i.e., the one who was the Fire Devil's host. Given that his name means 'hindsight/ afterthought,' it is intriguing that his narrative significance was realized when looking back, i.e., in hindsight. Denji's choice to save the cat and not the humans nearby set off a chain reaction.

The consequence of this action was the birth of a desire for revenge in the older brother. Witnessing his younger brother perish due to Chainsaw Man's misdeed led him to use the Fire Devil and its abilities to tread a path of vengeance. This is made even more compelling given the link to the Fire Devil, or rather fire, with the two brothers.
Not stealing fire per se, but the sibling duo helping the Fire Devil references them receiving the element. Their being bestowed with its power to do good is akin to humanity gaining the advantage. However, the younger one's demise compelled his brother to channel this power into retribution. It is tragic that now this power was fueling destruction, i.e., inverting Prometheus' act of compassion.
Denji may very well be Zeus here, an individual who was remiss, unaware of consequence, and catalyzing great suffering. Fujimoto's opting for an approach like this makes the Fire Devil a truly complex entity. Prometheus' pain is mirrored in the older sibling's being tormented by his brother's death— a reminder of Denji's negligence. His actions are both punishment and protest.
The entire Fire Devil incident is straightforward in conveying one thing— no matter what, consequences cannot be outrun as they will definitely catch up some day, and will do so in the most unforeseen of ways.
In conclusion

This Prometheus reference in Chainsaw Man is yet another example of Tatsuki Fujimoto's intricate storytelling style. No detail is spared, and all of them are equally important. The consequences of Denji's actions from over a 100 chapters ago deserve loud applause for how it was implemented. It was another curveball by the mangaka, and a brilliant one at that.
At the same time, it presents Denji as one of the most organic and evolving protagonists in Shonen animanga. Even after 205 chapters, he is still making mistakes and growing. But now, it is time for him to face the repercussions of his misdeeds. Not to be mistaken, he had suffered quite a bit, but amidst this, he too has committed his fair share of sins, for which atonement is en route.
Also read:
- Chainsaw Man chapter 205 highlights
- Chainsaw Man: Fujimoto uses Fire Devil to make the ultimate Fire Punch reference
- I think Denji's obsession with fame is Chainsaw Man's biggest clue to Pochita's true identity