The series is set in the year 2517, after the arrival of humans in a new star system, and follows the adventures of the renegade crew of Serenity, a "Firefly-class" spaceship. The ensemble cast portrays the nine characters who live on Serenity. Whedon pitched the show as "nine people looking into the blackness of space and seeing nine different things".
The show explores the lives of people who fought on the losing side of a civil war who now make a living on the outskirts of the society, as part of the pioneer culture that exists on the fringes of their star system. In addition, it is a future where the only two surviving superpowers, the United States and China, fused to form the central federal government, called the Alliance, resulting in the fusion of the two cultures as well. According to Whedon's vision, "nothing will change in the future: technology will advance, but we will still have the same political, moral, and ethical problems as today."
- Malcolm "Mal" Reynolds: the owner of Serenity and former Independent sergeant in the pivotal Battle of Serenity Valley. Very little is known about the enigmatic Captain; the little he reveals about his past life betrays nothing of his character (a mystery of its own). Malcolm reveals that he grew up on a ranch, and was raised by his mother and the ranch hands. The only other scenes of his past life that are shown are about the Unification War, in which he and Zoe fought for the Independent Army, the "Browncoats", as a platoon sergeant in the 57th Overlanders. He is an efficient leader and is skilled with guns as well as in hand-to-hand combat. Mal's character is full of contradictions. He is constantly fighting his demons, and his true self remains something of a mystery.
- Zoe Alleyne Washburne: second-in-command onboard Serenity, a loyal wartime friend of Captain Reynolds, and the wife of Wash. Described by her husband as a "warrior woman", she has great knowledge of combat. Her past is a mystery; the only thing known is that she was born and raised on a ship and served under Mal during the war as a corporal. She demonstrates an almost unconditional loyalty to Mal, the only exception noted being her marriage to Wash, which the captain claims was against his orders.
- Hoban "Wash" Washburne: Serenity's pilot and Zoe's husband. Wash expresses jealousy over his wife's "war buddy" relationship and unconditional support of their captain, most particularly in the episode "War Stories", in which he confronts Mal regarding their relationship. While more of Wash's past is disclosed than most other characters, his background is still sparse: he joined pilot training just to see the stars, which were invisible from the surface of his polluted homeworld, and he joined Serenity despite being highly sought after by other ships. He is very light-hearted and tends to make amusing comments, despite the severity of any situation.
- Inara Serra: a Companion, which is the 26th century equivalent of a courtesan or oiran, who rents one of the Serenity's two small shuttles. Like her Renaissance counterparts, Inara enjoys high social standing. Her presence confers a degree of legitimacy and social acceptance the crew of Serenity would not have without her on board. She and Mal have a strained relationship, with unspoken romantic tension playing a significant part in several episodes, as well as in the movie. Inara arguably represents Mal's heart, and Mal is a noticeably darker character when Inara is absent (as during the first half of "Serenity").
- Jayne Cobb: hired muscle. He and Mal met on opposite sides of a rivalry; Mal, while held at gunpoint, offered Jayne his own bunk and a higher cut than his current employer, so he turned coat and shot his then-partners. In one episode, he admits freely to Mal that he would have sold Mal out to an Alliance agent if the money was good enough. He is someone who can be depended on in a fight. He tends to act like a "lummox" who thinks he is the smartest person in space, but occasional hints of intelligence peek through this façade, giving the impression that he acts dumber than he is. As Whedon states several times, Jayne is the man who will ask the questions that no one else wants to. Even though he is a macho character, he has shown a particularly intense fear of Reavers, more so than the rest of the crew. Despite his amoral mercenary persona, he sends a significant portion of his income to his mother.
- Kaywinnit Lee "Kaylee" Frye: the ship's mechanic. In the episode "Out of Gas", it is established that she has no formal training, but keeps Serenity running with an intuitive gift for the workings of mechanical equipment. Jewel Staite explains Kaylee's character as being wholesome, sweet, and "completely genuine in that sweetness", adding "She loves being on that ship. She loves all of those people. And she's the only one who loves all of them incredibly genuinely." She has a crush on Dr. Simon Tam. Kaylee is the heart of the ship: according to creator Joss Whedon, if Kaylee believes something, it is true.
- Dr. Simon Tam: a medical researcher and trauma surgeon of the first caliber (top 3% in his class at a top core-planet institution), who is on the run after breaking his sister River out of a government research facility. In the episode "Safe", it is revealed that he and River had a privileged upbringing with access to the best education. It is also revealed that Simon sacrificed a highly-successful future in medicine, over his stern father's severe objections, when he rescued River. His bumbling attempts at a romantic relationship with Kaylee are a recurring subplot throughout the series, and at every turn he seems to find a way to unwittingly foil his own attempts at romance. His life is defined by caring for his sister.
- River Tam: smuggled onto the ship by her brother. River was a child prodigy of unparalleled genius, but she was experimented upon at the hands of Alliance doctors, leaving her delusional, erratic, and at times violent. Her personal journey of self-discovery is a running theme throughout the series and the movie. River is constantly at war with her own demons. She sees and hears things that others do not, and experiences waking dreams of her memories of the Alliance "academy" experiments. Opinions of her vary among the crew: some value her, Jayne fears her, and the rest just want her to stay out of trouble. She is also telepathic, or, as Captain Malcolm Reynolds puts it in the episode "Out of Gas", a "reader".
- Derrial "Shepard" Book: a Shepherd (equivalent to a pastor). Although presented as a devout Christian man, Book demonstrates a depth of knowledge about the activities of criminals (in "Our Mrs. Reynolds") and corrupt police (in "The Message"). He is also proficient in hand-to-hand combat and the use of firearms. When questioned on his non-Biblical intentions during the rescue in "War Stories", Book replies somewhat ironically that while the Bible is quite specific about killing, it's "somewhat fuzzier on the subject of kneecaps." In "Safe", he was shown to have sufficient status in the Alliance to receive medical treatment from the military with no questions asked. Book represents Mal's guide, conscience, and lost spirituality, while his hidden backstory was to have been gradually revealed, had the series continued.
Other Characters / Groups
- Union of Allied Planets (aka The Alliance): a powerful authoritarian government and law-enforcement organization that controls the majority of territory within the known universe. Originally composed solely of a number of "core worlds", several years prior to the show's timeframe the Alliance fought the Unification War to bring all colonized worlds under its control.
- Reavers: Appear in multiple episodes, and constantly feared by the FireFly crew, Reavers are hardcore rapist cannibals. Reavers are basically space pirates, who attack not only ships but planetary colonies as well. Reavers are readily recognized in any situation by both appearance and behavior. Whether ritually or in fits of rage, they maim themselves, peeling off parts of their own skins and shoving pieces of metal into the flesh. Reavers are savage, brutal and primal, though they engage in some form of social behavior and cooperation within their own group. Their contact with normal humans appears limited to combat, rape, torture, murder, and cannibalism. These contacts are brief and survivors few. As a result, little is known of Reavers' social structure.They live way out beyond the outer colonies, and no one dares to fly into Reaver space.
Exceeding the Human Body
In Firefly, River Tam was experiment on by the Alliance. They lobotomized her brain, paying special attention to areas that regulate self control and emotional stability. They had hoped to awaken some sort of extra sensory perception and succeeded. It was never clear what powers she had specifically, it is obvious that she gain some kind of awareness that human beings do not innately posses, allowing her to exceed the natural limits of her body. In some ways this could be seen as unwillingly becoming a cyborg. Due to the definition of a cyborg as a person with technological enhancements, meaning that because she gained ability power from this experiment, technology has helped benefit her, making her a cyborg.
What Is Human
During class discussions, we often questioned what qualifies something as human and discussed examples such as artificial intelligences and cyborgs. However, the Reavers are something altogether different. Often demonized by those who do not know any better, Reavers were born human and became savages due to exposure to a airborne chemical substance. This substance changes their behavior, making them violent, primal, and self destructive. Characters in the show have varying opinions on the Reavers. Malcolm Reynolds views them as tortured souls who have their humanity. Jayne Cobb sees them as savage man-animals that should be left alone. Sheppard Book describes them as men who have simply lost the light of civilization and need to be reeducated in the ways of humanity. All the varying viewpoints have a basis in the Firefly universe, leaving the question of whether the Reavers are human or not.