FL4K's sexuality has been confirmed on multiple occasions as omnisexual and "omniflirtatious." They do recognize that sex is a thing, though are still trying to figure it out. Whether this is due to their being a robot or otherwise is currently unknown. FL4K's most common and default appearance is their hooded and clothed form; they wear a large, oversized, and tattered series of jackets and shirts which has a hood and multiple pockets. They have one shoe and a more robotic foot, as well as wearing large shoulder pads (one of which has a patch of a skull) and an arm cover on their left forearm. On the collar of their jacket, they have two pins; one of a smiley-face with jagged teeth, and the other "010" crossed out with a non-binary colored cross (a joke in reference to the fact they are non-binary). They always wear a backpack with a pink, spiky food bowl dangling from it. Their robotic body has a single glowing eye in the head and more spindly limbs. FL4K is obsessed with death and has the impression that he should do anything appease her. It's unknown how or why FL4K devolved these thoughts but he has. It's unknown why FL4K even knows of the concept of death; he's constantly on the verge of trying to please death herself. FL4K does by activating the "hunt" to please the persona of death itself. FL4K is a sadistic thrilling seeking mercenary. Despite how homicidal and sadistic FL4K is, he has a much more calming and nice side to him. He enjoys hanging out with animals and treating them if they're injured or wounded. FL4K hates it when other people hurt animals or violent them in any kind of way. FL4K states that if he could he would slaughter anyone who dares to hurt animals. FL4K tends to show his more sadistic side when fighting people whom he considers to be cruel and or evil. Of all the Vault Hunters, FL4K is among the harshest and bluntest in terms of personality. FL4K served as an "Indexing Unit" under the command of a man known as the "Grand Archivist", sometime before the events of Borderlands 3. Their employment was cut short when FL4K suddenly acquired self-awareness and a "thirst for murder," as FL4K puts it. At this time, it is unknown what brought about this sudden change in FL4K, or which archives FL4K and their master were responsible for. After gaining self-awareness, FL4K now roams from world to world seeking self-discovery. While they feel a connection with the primal wisdom of animals (and thus always have a pet companion with them), the social constructs of humans are strange to them. FL4K has an unending goal to chase "The Hunt", an apparent belief of hunting as a way of life; they pursue The Hunt in an attempt to please "Mistress Death", a personification of Death itself. FL4K is joined by a Spiderant Centurion companion that imparts FL4K with health regeneration. FL4K spends hours looking at cool frogs on the ECHOnet. FL4K dislikes the texture of tapioca.