The Borderlands games are full of Easter eggs and references to pop culture, but there’s one thread running through them that hints at a far more story-oriented secret lying under the series’ surface. Borderlands 3’s FL4K, the beastmaster player character, brought this theory to a head and made many fans hopeful that the plotline would be addressed in one of the game’s DLC story campaigns, or at least by the developer eentually.
There is a theory that developed before but was given more proof with the release of Borderlands 3, and that's a connection between FL4K, Zer0, and 0ne. Many believe they are all robots, and are all related to one another. This relies on a few other heavily-hinted theories being confirmed, but once it’s all laid out, it’s hard for many Borderlands fans to resist making the connection. Here’s the 0ne, Zer0, and FL4K theory in full.
Zer0 the Assassin
Ever since Borderlands 2 released, there have been rumors that Zer0, the assassin player character, is a robot. There are a few pieces of evidence which point to this. When looking at Zer0’s design, it is difficult to say where the suit ends and the person – if there is one – begins. If players look at Zer0’s knees, for example, the figure exposed under the armor playing seems almost too thin to be human. Of course, the Borderlands series is highly stylized in its design, and this could be a part of that artistic direction.
However, Zer0 is also missing two fingers, operating a sniper rifle with just four fingers on each hand. These missing fingers don’t appear to be the result of injuries, as Zer0’s hands seem perfectly proportioned to have just four fingers each. While there are plenty of cartoons which have characters with four-fingered hands in order to simplify their designs, so far Borderlands has not been one of those series, with all explicitly human characters having the normal number of digits.
Zer0 doesn’t run out of breath when running in the same way that the other vault hunters do, and when he speaks, his voice is ostensibly distorted by his mask to make him sound robotic. There’s a lot of evidence which point towards Zer0 being a robot, and its even hinted at by Angel, a siren in Borderlands, who comments that she isn’t sure if Zer0 is human or not. FL4K is explicitly a robot, leading some Borderlands fans to speculate that the two may be related in some shape or form.
FL4K and 0ne
FL4K appears less robotic than Zer0 at first, with FL4K’s huge coat helping to cover the fact that he shares Zer0’s slim frame underneath. FL4K’s design, however, establishes a few things about this kind of robot in the world of Borderlands which makes it appear far more likely that they can count Zer0 among their ranks.
Like Zer0, FL4K only has four fingers on each hand. Both characters have numbers in their names, though FL4K himself is not named after a number. Both characters are able to cloak in a similar way, which implies that it could be due to some technology inherent in their creation rather than a device the characters are using. It may even help fans figure out what FL4K and Zer0’s original purposes were when they were created.
There is another character who shows up in the DLC Sir Hammerlock vs. the Son of Crawmerax, who helps support the theory that Zer0 and FL4K are related. In the DLC, Zer0 is helped by a character known as 0ne. At the end of the missions, Zer0 receives a message from someone who presumably killed one of the assassins sent to stop the vault hunters completing their task. The message reads “To Zer0; 0ne.”
This heavily implies that Zer0 was part of some kind of line of assassin robots which 0ne was also a part of. The 0 shared in both of their names could imply that both of these characters are prototypes of the same kind of robot. The fact that FL4K’s name includes a number but not the number 0 could imply that FL4K is either part of a completely different line – perhaps one better designed to be a beastmaster – or it could imply that only the numbers in the robots’ names matter as an indication of their model, while the rest of their name is taken just to distinguish the individual robot.
When FL4K and Zer0 meet in Borderlands 3, FL4K even refers to Zer0 as feeling “familiar” despite the fact that they are meeting for the first time. Based on their appearances, it seems like that FL4K and Zer0 were created by the same company if not for the same purpose. If they were made at the same facility, this could help explain how Katagawa Jr was able to mimic Zer0’s suit, as presumably whatever design was used to produce Zer0 was also used to create 0ne and FL4K and still exists somewhere in Borderlands’ galaxy. On top of this, Zer0 appears to knowingly question himself about how Katagawa could have gotten the tech.
If nothing else, the theory that Zer0 is a robot is overwhelmingly supported by in-game evidence. FL4K recognizing Zer0 and Zer0 still not being fully identified as a robot may even be an in-joke across the two Borderlands games in which he appears. Fans will have to wait and see whether Gearbox will reveal the origins of Zer0 and FL4K in the next game in the series.
Borderlands 3 is available now on PC, PS4, PS5, Stadia, Xbox One, and Xbox Series X.