Kaido’s Lineage Factor/Bloodline Element has become a substantial aspect to the research conducted by Vegapunk and the Marine Scientists. The CP-0 have already confirmed that when Kaido was captured by the Marines he was experimented on with his Bloodline Element being used by Vegapunk to create the Artificial Devil Fruit that Momonosuke has consumed. Beyond the Artificial Devil Fruit there are also connections with Kaido’s Bloodline Element being used to experiment on the Numbers. The connections they share with Kaido are too substantial to ignore as separate. Additionally, the Dragons Vegapunk developed also appear to be based on his research into Kaido’s Bloodline Element. Further, there may have been other subjects that were used in the research into Kaido’s Bloodline Element, specifically, the Jailer Beasts of Impel Down. The blood Kaido possess has become an incredibly valuable component in the Marines research in creating “weapons” that can strengthen their forces and I find myself curious as to how else the Marine Scientists (and Vegapunk) have weaponized Kaido’s Bloodline Element. Will Kaido’s blood and ancestry become a core story thread going forward as the secrets of the past hidden away by the World Government are uncovered?
The reasoning for why I believe Kaido’s Bloodline Element was used in the experimentation of the “Numbers” is because of the shared characteristics they have with Kaido and the interest Kaido took in them. The Numbers have displayed certain features and tendencies similar to Kaido (oni-features), mainly the horns and the love for alcohol. Kaido and the Numbers also share in the use of the same type of weapon – kanabō. Kaido could have realised the connection he had with the Numbers when they went up for sale on the black market and consequently purchased them as Big Mom mentioned.
In addition, the Dragons Vegapunk created to serve as guards of Punk Hazard (Dragon Number Thirteen and Small Dragon) are likely also based off his research into Kaido’s Bloodline Element. The naming convention of the Numbers and Dragon Number Thirteen suggest some connection regardless of the Dragon being named by a Tenryuubito. The reason the Dragons survived the Shinokuni poison from four years ago when Caesar activated his weapon and the battle between Sakazuki and Kuzan could be the result of having Kaido’s Bloodline Element. In addition to the thick skin, the flame breath could also have been the result of Kaido’s blood.
Turning to the Jailer Beast, what makes me believe they are related to Kaido? There isn’t anything definitive but rather an interpretation framed by reading between the lines. Something was clearly odd with the Jailer Beast when they were featured during the Impel Down Arc. Not only were their humans forms not revealed but their exact Devil Fruits were also kept a mystery not to mention the absence of speech. The Jailer Beasts may have been the initial attempts by the Marine Scientists at utilising Kaido’s Bloodline Element to enhance a soldier. Could Kaido’s blood have brought the Jailer Beast to a sort-of awakening Zoan state? Was this the original intent of the experiments on the Jailer Beast? The side-effects of such experiments could have rendered the Jailer Beast unable to shift back into human form and the loss of speech. The scene where Kaido viciously beats Yamato while he is on the ground in chapter 1025 reminded me of Minotaurus beating Jinbe while he was imprisoned in Impel Down. It could be a coincidence but when you also take into account the club and spike weaponry the Jailer Beast use and their “fish” lips (as a result of the Uo Uo no Mi), one does wonder if there really is no connection between Kaido and the Jailer Beasts.
With such mystery remaining around Kaido, it becomes curious thinking about the reasons for why the Marines took a immense interest in him. Were they not able to kill him when captured and as such resorted to extracting his DNA to research? But what makes Kaido so special? Sure, he has the Mythical Zoan Dragon Devil Fruit which the World Government would be interested in but what about the rest of the research that appears to almost certainly have been conducted with the data derived from Kaido? With the Marine Scientists and Vegapunk using Kaido’s Bloodline Element as a component in their research for creating Ancient Giants, would this imply that Kaido himself is also part Ancient Giant? After Kaido mentions to Yamato during their battle in chapter 1025 that they contain the blood of Oni/Ogres, I believe that the Ancient Giant tribe – which has not yet been named – are the Oni/Ogres Kaido mentions. Yes, the Ancient Giant tribe are Oni/Ogres.
Not only does Kaido bear a striking resemblance to the Ancients Giants we have seen so far in the manga – Oars and Little Oars Jr – but he is also associated with Punk Hazard which is in turn linked to the story of Ancient Giants. Beyond the experiments conducted on the Numbers, Punk Hazard also contains other elements connecting it to the Ancient Giants; the larger-than-a-giant-skull with horns and the irregular warning symbol at the entrance of Punk Hazard. When all of this is taken together with the belief that Ancient Giants are Oni/Ogres, it makes complete sense why the Marines would take an immense interest in Kaido and the research into his Bloodline Element.
If Kaido truly is connected to the Ancient Giants, another question does arise – why would Oda-sensei be holding back details of it? Does he intend to connect such a narrative to the upcoming Vegapunk and Giant stories? And how will Yamato, who shares the same blood as Kaido, fit into that narrative? Will the Marines consequently take an interest in Yamato when they find out his connection to Kaido? I suspect, like King, Kaido also belongs to an ancient race (Oni/Ogres) where implications of those races’ history will be covered down the line which Yamato will hold relevance in.