Warning: Contains spoilers for One Piece chapter #1138.For over a decade, one of the biggest questions inOne Piecehas been how Blackbeard stole Whitebeard’s Tremor-Tremor Fruit while still possessing his original Dark-Dark Fruit. People only being able to eat one Devil Fruit at a time was one of the strictest rules of the setting, and Blackbeard so casually breaking it has sparked countless debates over possible explanations, with some theories naturally taking off more than others.
Of all the theories for how Blackbeard could have multiple Devil Fruits, one of the biggest has been that he’s secretly eaten a hypothetical Cerberus Devil Fruit. The idea is that a Cerberus would have three stomachs, thus letting Blackbeard circumvent the rule, and the Blackbeard Pirates’ Jolly Roger having three skulls was what most people cited as foreshadowing for that idea. That being said,One Piecechapter #1138has effectively killed the theory of Blackbeard having a Cerberus Devil Fruit with a single panel, although to be fair, the theory never had much weight to begin with.

How The One Piece Manga Killed One Of The Biggest Blackbeard Theories
One Of The Biggest Blackbeard Theories Is Officially Dead
InOne Piecechapter #1138,Figarland Shamrock of the Holy Knightsdecided to kill Loki for his repeated refusal to join the Holy Knights, but rather than do the deed himself, he has his sword transform into a giant, three-headed dog that is, naturally, called Cerberus. The obvious implication is that Shamrock’s sword is a rare inanimate object given the power of a Devil Fruit, specifically the Cerberus Devil Fruit, and because of that,One Piecehas officially killed the theory that Blackbeard has a Cerberus Devil Fruit by giving that power to Figarland Shamrock’s sword.
Things might not be so cut-and-dried, however. Much like the Five Elders, Shamrock’s sword wasn’t specifically noted to be a Devil Fruit user, despite having the same framing typically used for those reveals, so Shamrock’s sword could have been infused with power from Imu as opposed to a Devil Fruit. Even if that were the case, though, two separate characters having Cerberus-based powers would be undeniably redundant, soFigarland Shamrock’s Cerberus sword, whether it’s a Devil Fruit or something else, kills the idea of Blackbeard having a Cerberus Devil Fruit simply by existing.

One Piece’s Biggest Blackbeard Theory Never Made Sense
Why Blackbeard Having A Cerberus Devil Fruit Never Would Have Worked
WhileOne Piecechapter #1138 effectively killed the theory of Blackbeard having a Cerberus Devil Fruit, the theory never actually made much sense. The only explanation given for Blackbeard having multiple Devil Fruits was Marco stating that there’s something odd about Blackbeard’s body, but Zoans don’t typically change the user’s body when not actively in use, something Marco would know better than anyone. Because of that,the most logical explanation for Blackbeard’s ability to have multiple Devil Fruits is that it stems from his biology, not a Devil Fruit, and that was easy enough to grasp from day one.
Baron Tamago’s Egg-Egg Fruit is a Zoan that appears to be permanently active, but it’s likely a special case like how Katakuri’s Mochi-Mochi Fruit is a special Paramecia with properties of a Logia.
That idea is further supported by some dialogue in the Egghead arc. When Saint Saturn was confronted by the Blackbeard Pirates,Saint Saturn said that Blackbeard’s lineage was special, and while that wasn’t elaborated on, that means thatOne Piece’s Egghead arc has all but stated that Blackbeard’s ability to use multiple Devil Fruits comes from some unique lineage of his. The exact details of Blackbeard’s powers will hopefully be revealed soon, but whatever the case,One Piecechapter #1138 still makes as clear a case as any for what they aren’t.