Ennis del Mar
Ennis del Mar is a rough, uneducated ranch hand from Wyoming. His simple life is changed one summer when he meets Jack Twist. The two men become friends and passionate lovers. Ennis is torn between duty to his wife and his desire to be with Jack. After losing interest in their marriage, his wife divorces him. He goes from one menial job to another while sneaking away once or twice a year to spend time with Jack. Fearful of being discovered, and confused by his sexuality, Ennis refuses Jack's request to live together openly. Homosexuality is not socially accepted in the 1960s, and he is unable to do what Jack asks. After Jack tragically dies, Ennis is left with nothing but his memories of Brokeback Mountain and his dreams of Jack.
Jack Twist is a high school dropout and ranch hand from Wyoming. He loves the rodeo and wants to do more than just work on a ranch. He meets Ennis del Mar one summer, working on Brokeback Mountain. They become passionate lovers and Jack is inspired by this unexpected love. He wants Ennis to go away with him so they can work and live together on a ranch. Jack is less worried about someone discovering their homosexuality and more interested in indulging his desire for Ennis. He ends up moving to Texas where he meets Lureen, a woman with money from her father's business. They marry and have one son, but Jack is restless and longs for Ennis. He joins the rodeo and endures many injuries and broken bones. He finds time to go off with Ennis over the years, but he cannot convince him that they belong together. He dies tragically while fixing a flat tire. Ennis suspects that Jack was actually murdered for being a homosexual.
Joe Aguirre is the Forest Service foreman who hires Ennis and Jack to work on Brokeback Mountain. He views them as a pair of losers and gives them strict instructions on what they should do and where they should sleep. When Jack returns the following summer, Joe refuses to hire him and lets Jack know he was aware of what he and Ennis were doing up on the mountain. Jack sees Joe's binoculars and realizes that Joe must have spied on them.
Ennis and Alma Beers are engaged before Ennis meets Jack. They marry and have two girls. When Jack comes to visit Ennis, Alma discovers them kissing one another in the hallway but says nothing. Alma is unhappy with Ennis's lack of ambition and their constant money shortage. She resents that Ennis goes off with Jack for days at a time but never takes her or their girls on vacation. There's no spark in their marriage, and after 10 years she gets a divorce and marries the local grocer. One Thanksgiving Alma invites Ennis to dinner and informs him that she knew about his relationship with Jack. Ennis twists her wrist and leaves abruptly.
Lureen Twist possibly knows of Jack's desire to have money to finance his rodeo dreams and to invest in a ranch. However, she apparently does not approach her wealthy father for funds. Although it's not spelled out, it seems likely she knows the nature of Jack and Ennis's relationship.
John Twist is a homophobic, bitter man who knows, or suspects, that Jack was homosexual and, by extension, that Ennis is also. His refusal to surrender Jack's ashes is driven by spite, not a wish to keep his son's remains for sentimental reasons.
Mrs. Twist loves and misses her son. She keeps his childhood room intact as kind of a shrine to the son her husband drove away.