Foo Fighters

F.F. can reshape its form on a whim, but the look it settles into is that of the inmate Atroe, a woman of ordinary height and slender build whose hair or cap ends in a jagged, saw-toothed fringe. Because the whole body is really a mass of plankton, it can bend into shapes no human could and squeeze straight past prison bars unharmed.

Away from any water source it is usually seen clutching a large drinking cup. Its underlying Stand originally appears as a towering, dark, almost robotic humanoid with an alien face, though as F.F. grows into its own identity that true shape softens and takes on more human features.

At first F.F. is little more than a dutiful servant carrying out Pucci's commands, but contact with Jolyne slowly draws out a self of its own. It possesses sharp intellect paired with almost no lived experience, so in its earliest days its only concern is staying alive and guarding the discs, attacking any approaching stranger without mercy while insisting that enemies acknowledge it as a thinking, named being.

Everything changes once Jolyne shows it mercy and rescues it from drying out. From then on F.F. perceives the world as suddenly vivid and full of color, growing endlessly curious, peppering others with questions and testing what it can do. It bonds most deeply with Jolyne, who gave it both freedom and a mind, and it eventually comes to treasure its friends above its own survival. A relentless thirst rules its body, and it will drink any fluid that holds water, unbothered by what that fluid might be.

F.F. comes into being by accident when Pucci flings a spare Stand disc into the sea and it lands among a drifting patch of plankton, gifting the colony life and purpose. Ordered to protect the priest's hidden cache of discs and kill any intruder, it does exactly that until Jolyne and Ermes stumble upon the site. Beaten and left parched near death, it is spared by Jolyne, who gives it water; in gratitude it reveals the location of Jotaro's stolen Stand disc, then takes over a dead prisoner's body and follows the pair back inside.

Now traveling as Atroe, F.F. joins the group's ordeals, from a rigged game of catch against Miraschon to uncovering the truth of Ermes's murdered sister, and it heals its wounded companions at great cost to itself. Later it shields Jolyne from Kenzou and, after being lured into a trap by Pucci that knocks the Foo Fighters disc from its head, spends its dying strength sealing Anasui's wounds. Its spirit thanks Jolyne for their friendship and refuses to be revived, reasoning that any restored version would be a different F.F. rather than the one that truly lived.