Gavrill is the first of three girls created by Norihito Madaraki, the world’s greatest experimental surgeon and creator of medical oddities. However, unlike her younger sisters Fran, who inherited the good doctor’s surgical skills, and Veronica, who served as his bodyguard for some time, Gavrill was cast aside after she proved to be far too energy-intensive to be counted as a successful experiment.
After finding herself more or less alone in the world, Gavrill turned to a life of crime. As the head of a brutal gang responsible for a great number of crimes across the world. This has earned the elder Madaraki sister the title of The Wolf by others who have seen what she is capable of, is that when using her power of transformation she typically takes the form of a beast with a long muzzle much like that of the animal in question. As a gang leader, she tends to be capable of doing horrific things to get what she wants. These acts include the likes of robbery, murder, or even cannibalism, as she has on occasion boasted that she has eaten human beings. She is also noted as being a wanted criminal across the globe, and several countries teamed up with Fran in an attempt to get rid of Gavrill once and for all. This effort led to her being led to an island and given an endless collection of regenerating clones to fight. However, as Gavrill had overcome the ability of her targets to regenerate, she was eventually targeted with high powered missiles, which manages to destroy the island she was on, but merely made Gavrill herself angry.
Aside from being a wanted criminal, Gavrill also boasts a vocabulary that could charitably be called vulgar. Her typical speech is littered with swearing and cursing, typically of the variety that includes words such as fuck and shit, and tends to speak to others in ways that derogatory to the point of absurdity, such as when she mentioned that she could smell Fran’s “rotting cunt” during her assault on her sister’s manor.
What she seems to want most out of life, however, is to take what Dr. Madaraki has given to Fran as his legacy for herself. We see this in the chapter in which Gavirl debuts, in which she finally manages to track down Fran and Veronica and wages an infiltration of their home to claim what she believes to be rightfully hers. We see during the attack that Gavrill is utterly ruthless and will do almost anything to get the job done. This is seen when attacks and dismembers Veronica who had attempted to attack her to stop the rampage only to be gutted and left for dead until Fran patched her up. The attempted theft saw Fran blow up Gavrill with a bomb, which had little impact given Gavrill’s near invulnerability. From this, we can see what little love Gavrill has for her sisters, and her gang, which she more or less leaves to die as she attempts to find Fran herself.
However, though Gavrill is not the greatest person in the world, and indeed kind of a weirdo in general, there is one person in the world she trusts. That being Dr. Madaraki’s old friend Dr. Amatsuka. This old man, a friend of Madaraki from their days serving in World War 2, is one of the few people that Gavrill is close to. Though this is partly because Amatsuka is the only person on Earth who can calibrate Gavrill’s body and prevent it from falling apart, she also respects him as a person and will take on jobs for him on occasion. We see this twice across the series, the first when Amatsuka is hurt by thugs hired by a corrupt politician, which saw Gavrill track down the offender and bite off his head.
The second saw Gavrill acting as a substitute high school teacher. As a teacher, Gavrill quickly becomes known as a brutally honest person who gives her students advise that might be incredibly blunt but ultimately has some basis in reality. For example, when talking to a boy who was going to commit suicide due to being bullied that the best revenge for such a situation is to keep living. Less positive advice includes telling a poor girl to get knocked up by a rich kid, or a boy who wants to be popular with girls to get plastic surgery. She also seems to have some love for the kids she teaches, as she goes out of her way to kill off several kidnappers attempting to force their parents to pay them for their kids’ release.
In general, Gavrill is a terrible person who is not only the leader of an infamous gag but also has no qualms about killing people and committing crimes. However, when she acting for those she has some affection for, such as Dr. Amatsuka, or the kids that she teaches, she is capable of using her various powers to help them, even if that help comes in the form of more brutality and advice that is far to straight forward and blunt.
Powers
The entirety of Gavrill’s body is separated into partitions that can be shifted around with her thoughts and controlled by a band on her head with what looks like egg timers on either side. This allows her to transform into a variety of different forms, the most common of which is a giant wolf-like monsters with a mouth full of shark-like teeth, though she has also taken on the form of a small child to hide herself on at least one occasion.
In addition, she can also temporarily change the size and shape of individual body part at will, this is often seen when she hardens her skin to avoid taking damage from attacks, as well as her transforming only her head in order to take advantage of her wolf-form’s huge jaw without changing the rest of her body.
An in-universe explanation of this can be seen in the following manga panel https://imgur.com/a/0tmdW4S.
Gavrill also possesses several superhuman powers that seem to be unrelated to her shape shifting powers. For one, she is nearly impossible to harm by normal means due to her shapeshifting ability, and has been shown to be able to survive everything from a conventional explosives, to military grade missiles while sustaining very little damage in the process. She also has an amazing sense of smell, claiming on one occasion that she is able to smell the pheromones of other living beings.