Foo Fighters

Foo Fighters (commonly referred to as F.F) is an ally of Jolyne Cujoh featured in Part VI: Stone Ocean.

Personality
F.F was shown not to have much eye for detail prior to meeting Jolyne Cujoh and Hermes Costello, and laments its pitiful existence upon expecting death after being defeated by the two. When Jolyne saves her, however, F.F immediately begins to notice more details around her, and she began to perceive the world around her as being more colorful. Although she likes the other people she has met, she has the strongest affinity for Jolyne for giving her freedom.

F.F is commonly shown carrying a 32 oz. cup near her when she is not near a water source.

Birth
Enrico Pucci had a shack of Stand disks near prison grounds, a collection of different Stands that he had collected over the years while in prison. The area around the shack is generally untouched and desolate. Enrico needed a guardian for these disks, lest they fall into unwanted hands. He threw a random stand disc into the ocean, which hit plankton floating on the surface. Unexpectedly, F.F was born.

Stone Ocean (2011-2012)
F.F, or Foo Fighters, was told to stay there by Pucci and to kill anyone (other than him) should they come close. Having no other purpose, it did as it was told. When Jolyne and Hermes approached the shack during an outdoor activity, F.F attacked but was soundly beaten by both of them. Parched and close to disintegrating, it lamented its meaningless life, but was spared by Jolyne, who gave it water, despite Hermes' protests. Fascinated by its savior, it showed Jolyne her father's missing stand disc in gratitude. Subsequently, F.F inhabited the body of a dead inmate and followed both of them back to prison.

Later, tricked by Pucci, F.F leads its friends into an ambush and suffers a severe blow to its body, knocking its stand disc from its head. Dehydrated and nearing death, it was able to hear the dying Narciso Anasui's request. He gave it permission to possess his body to pluck Jotaro's memory disk from him, not caring what happened to him as long as Jolyne would be happy. F.F did pluck Jotaro's memory disk from Anasui's body but refused to possess it. Its spirit (strangely taking on the form of Etro's body) heals Anasui's wounds and thanks Jolyne for being her friend, glad that they met. When Jolyne decided to retrieve the disk to revive her, F.F declines, saying that it would not be the real her, but another F.F and disappears into the wind.

Trivia

 * Due to her plankton inhabiting the body it is in, F.F can contort in impossible curves and even slip through barred fences unharmed.
 * True to its word, F.F was the only protagonist to not have a Steel Ball Run counterpart at the end of Part 6.
 * The origin of the name Foo Fighters actually derives from an American comic "Smokey Stover" which was a comic about a Fire Fighter. The comic commonly used the nonsense word "Foo." In World War II, UFO's that resembled balls of fire were labeled as "Foo Fighters" in reference to the word foo and fire fighter used in Smokey Stover. This UFO would later become the namesake of the rock band Foo Fighters. F.F's affinity to water could be a reference to the fire fighter in Smokey Stover, who mainly relies on water to extinguish flames.
 * F.F is the primary gun-wielder in Part VI, Starting from Part I & excepting Part IV, there is at least one person who used a gun in some way be it a stand or not, including Speedwagon, Stroheim, Hol Horse, Mista, & Johnny Joestar.