A character arc is the status of the character as it unfolds throughout the story, the storyline or series of episodes. Characters begin the story with a certain viewpoint and, through events in the story, that viewpoint changes. A character arc generally only affects the main character in a story, though other characters can go through similar changes.
Some examples include:
In Tootsie, Dustin Hoffman’s character begins as a misogynistic chauvinist but when he is forced to play the part of a woman, he also experiences a change in how he views women and becomes a different character by the end.
In Empire of the Sun, Jim begins as a carefree young boy. After the Japanese take over Shanghai and he is separated from his family, he is forced to suffer trauma because of the war.
In The Godfather, Michael Corleone at first does not want to have anything to do with his father’s crime business. When his father is attacked and barely survives, Michael begins a war of retribution on those responsible. This effectively and ironically sets him down the path to becoming the head of his father's crime syndicate. The Godfather Part II chronicles Michael's effective fall from grace as a result of becoming a powerful crime lord.
In Taxi Driver, Travis Bickle degenerates from a somewhat disturbed, highly disorganized Vietnam war veteran into an extremely highly organized, full-blown psychotic.
Unlike a story arc, the character arc is not confined within the limits of one story. The character arc may extend over to the next story, a sequel, or another episode. In episodic TV series, the character arc has become a hook that writers often use to ensure viewers continue watching.
In the American television series Lost, Shannon Rutherford is a damaged rich-girl who regularly cons money out of her stepbrother, Boone Carlyle, after his mother steals her inheritance. After the crash of Oceanic Flight 815, her knowledge of French is key in translating Danielle Rousseau's distress call. But her attitude following this event is generally one of being rude to the other survivors and unhelpful, as she believes rescue to be imminent. When, after a month, it looks like rescue isn't coming, and the constant attacks from her stepbrother in which he calls her "useless", she begins to help where she can and even develops a romantic relationship with Sayid Jarrah and befriends Claire Littleton, Sun-Hwa Kwon and Walt Lloyd. When Boone is killed, she reverts to being distant and angry. Walt, a young boy who survived the crash, entrusts his dog to Shannon when he and a few other survivors leave on a raft. Shannon later begins seeing visions of Walt, though no one believes her. She searches for him in the jungle before she gets into a tearful confrontation with Sayid. She asks him why he doesn't believe her, and why he doesn't believe IN her. Shannon thinks she is useless and therefore worthless, and is afraid that once they've been rescued Sayid will leave her just like everyone else has. Sayid tells her he does believe her, and that he loves her and will never leave her. They embrace before Shannon sees Walt again, and this time Sayid sees him as well. Shannon chases after him and is accidentally shot and killed by Ana Lucia Cortez, another survivor. Like many characters on the show, Shannon dies following the resolution of her personal issues.
The TV series Desperate Housewives made heavy use of character arcs throughout its run, with story arcs (or mysteries, as the show was famed for) normally being used to move the plot along in the background, as the four protagonists, Susan Mayer, Lynette Scavo, Bree Van de Kamp, and Gabrielle Solis, dealt with their various foibles and flaws, through the eyes of their dead friend and neighbour, Mary Alice Young. From the pilot to the series finale, the characters are shown to have come full circle, having dealt with their fears, vulnerabilities and flaws enough to move away from Wisteria Lane and begin new, happier lives, being free from the shackles of secrets and desperation that constricted them throughout the series. Susan, who began the series as a vulnerable single mother who is searching for love, goes through various quests for happiness and romantic fulfilment, and ends the series having been widowed, being a single mother to a young son, and having a new grandchild to look after. The similarities of the opening and closing situations allow the audience to see how much Susan has grown as a person; her sense of hopelessness and desperation has been replaced by a renewed vigour and hope for the unknowns of the future upon which she is embarking. Lynette started off as the drowning mother of four children who felt that her happiness was a sacrifice she had to make in order to raise them, while by the end of the series, she has become content with her life, having realised that happiness comes not from external conditions, but from within. While, throughout the series she is constantly shown to be searching for something more, something that will make her truly 'happy', this epiphany allows her to stop searching for the thing which she already has, and in turn lets her leave the Lane and take a new job in New York with her family. When we first see Bree, she is introduced as the wife and mother who is striving so desperately for perfection, for her vision of an 'ideal' life, and as a result she represses her fears and emotions, and is burdened by the secrets which are a by-product of this struggle. Ironically, as the series progresses, Bree has the most tragic, imperfect and unhappy arc of the four protagonists, until she eventually learns to let go of her struggle for idealism and fall in love with someone who loves her for who she is, ultimately learning that she cannot control every aspect of her life, but that only by letting go of her fears and secrets can she truly be happy. Gabrielle begins the story by being plagued by her and her husband's selfishness and greed, believing that contentment can come from wealth and materialism. As the series progresses, she is shown to make various selfish decisions to better her own cause and to protect herself from the consequences of her own mistakes. Ultimately, she realises that she loves her children, her husband and her friends far more than she loves herself, which allows her to become more selfless and find true happiness in what she has.
In Gargoyles (first US air date: October 1994 (1994-10)) (animated), the coming of age of Brooklyn is subtly portrayed as his difficulties in his personal life and his eventual promotion and adjustment to the clan's second in command position develop until they simultaneously come to a head when Goliath, Elisa and Bronx disappear on their world tour.
Over the course of the television series Xena: Warrior Princess (first US air date: September 1995 (1995-09)), Gabrielle starts from a young, idealistic Greek farm girl to becoming a warrior, and in the end, she becomes Xena's successor.
Jackie Burkhart (from That '70s Show (first US air date: August 1998 (1998-08)) goes from a spoiled ditsy rich girl that nobody liked, to a girl that was actually accepted in the group, while Michael Kelso starts off as an irresponsible womanizer but eventually settles down and gets a real job to support his family after the birth of his first child.
Smallville (first US air date: October 2001 (2001-10)) focuses on character arcs for each of its main characters as they progress into their Superman comic book identities. Clark Kent's arc revolved around the gradual acceptance of his destiny and becoming a hero. The series also tracks Lex Luthor's progression into darkness and Lois Lane's emulation of her cousin Chloe as she becomes a hardened journalist. Other characters have their eventual character arc alluded to but never explicitly defined or realized onscreen, such as Perry White's rise to editor of the Daily Planet and Pete Ross's ascension to Vice President of the United States. As well as individual characters, there are arcs involving many characters which intertwine to tell the formation of the Justice League.