Fredo was born to Vito and Carmela Corleone in 1919. In his youth he was a sickly child, contracting pneumonia as a baby. Growing up, he was an aggressive young man, despite briefly wishing to become a priest after meeting Father Stefano, but it was believed that Stefano molested him, leading him to abandon his training.
Fredo and the Family
As an adult he was seen as the weakest of the three brothers and was given relatively unimportant business to run. However, he was also known as a charismatic young man, and was usually sent to pick important people up at the airport and entertain them before business meetings. Although not tough enough to earn his father’s approval he was dearly loved by his mother. His failure to protect his father from an assassination attempt contributed to his sense of inferiority.
Move to Nevada
Fredo later moved to Las Vegas and was taken by Moe Greene as a favor to the family, who were funded by Anthony Molinari from the West Coast. Greene never treated Fredo as an equal partner however, becoming irritated by Fredo's womanizing activities, and even put him in danger by having him dispose of a business partner's body.
When Moe refused to sell out to Michael, Fredo attempted to defend him and was told never to side against the family again. Greene was later killed in 1955. Fredo's behavior in Vegas was considered embarrassing to the family, largely because of his notorious habit of impregnating showgirls and prostitutes.
Life after Las Vegas
Fredo was appointed sotto capo, or underboss, by his brother, an appointment that was seen as unqualified nepotism. Michael Corleone's rivals, chiefly Louie Russo, the mob boss of Chicago, hoped to exploit this rumor of Fredo's child molestation to make Michael look weak. In Las Vegas, he met Marguerite Duvall, who was sent up to his room by Johnny Fontane as a prank. Though hesitant at first, Fredo paid her three thousand dollars to tell Johnny it was the best sex she ever had, before eventually succumbing and sleeping with her. Shortly after, with Fredo's knowledge, Marguerite had a baby, who she put up for adoption.
Plans for the family
At the funeral for Don Molinari of San Francisco, Fredo got the idea of setting up a necropolis similar to Colma in New Jersey. The Corleone family would be able to buy up the former cemetery land cheap, now prime real estate, and also be a silent partner in the graveyard business. Fredo would propose this plan to Mike and impress him, reassuring him and others of his abilities. To Fredo's dismay, Michael would end up not going for it.
At the Christmas of 1956, Fredo showed up at the Corleone Christmas party with Deanna Dunn, a famous, yet by this time, fading, movie starlet. A few months later they got married. Dunn got Fredo to make appearances in bit parts in some of her movies. Later, in September 1957, Fredo's Hollywood connections allowed him to get his own successful TV show, "The Fred Corleone Show", which aired irregularly, usually on Monday nights, until his death in 1959, on a local television station in Nevada. Fredo's drinking problems continued and accelerated. One day, he discovered Deanna cheating on him with her movie co-star Matt Marshall, and Fredo shot-up the Corvette he had bought her. When Deanna's co-star tried to attack him, Fredo ended up knocking him unconscious with a pistol whip and went to a local jail. Tom Hagen came to bail him out and got in an argument about Fredo's reckless activity and Tom's blind loyalty to Michael. Tom again got the charges lessened to self defense after paying off Marshall and the hotel.
Nick Geraci met with Don Vincent "The Jew" Forlenza, the Don of Cleveland, and discussed how Fredo could fit into their plans to take down Michael. The deal with Hyman Roth had now reached a stalemate, and they figured Fredo could be used as a pawn to let Hyman Roth succeed. If Fredo was told they could help him with his Colma vision, he'd do anything to help. Fredo met with Johnny Ola and supplied him with all the information they needed, especially financial information, about the Corleone family. Fredo ambiguously claimed that his goal in that deal was simply to get something for himself, on his own, and swore that he did not realize he was being used as part of a larger plot to kill his brother. However, in the event of Michael's assassination, Fredo would likely have led the Corleone family, at least as a figurehead.
Michael discovered Fredo's role in the plot during his trip to Havana, when Fredo let it slip out that he and Johnny Ola had been in Havana together earlier that year and they went to the sex show together.
Michael confronted Fredo later and tells his older brother, "You broke my heart." Fredo flees in fear of his life, but he is actually in no danger because Michael believes that Johnny Ola and Hyman Roth had lied to Fredo and manipulated him. Later, when Michael is being pursued by a Congressional Committee investigating organized crime, he has a talk with Fredo and realizes that Fredo had both withheld important information from him about Hyman Roth's connection with the Committee's lawyer Questadt, was deeply resentful and jealous of Michael's role in the family business and the fact, that he was treated as an errand boy and that he was stepped over. Michael therefore disowns and banishes him from the family, although not wanting any harm to happen to him, while their mother was still alive.
Upon their mother's death, and at the urging of their sister Connie, Michael relented toward Fredo and seemingly offered reconciliation. However, it was only a deception to draw Fredo in so as to have him murdered by Al Neri.
Fredo and his nephew, Michael's son Anthony, developed a relationship with Michael's consent as part of a plan to kill Fredo and were to go fishing on Lake Tahoe. However, Anthony is called away by Connie, who tells him that his father wants to take him to Reno. Fredo is left alone in the fishing boat with Al Neri and he takes the boat far out onto the lake. His suspicions prior to his death are left up to interpretation. As Fredo prays the Hail Mary (which he claimed brought him luck whilst fishing), Neri shoots him in the back of the head, not knowing that Anthony was watching from his bedroom window, and had a deep resentment toward his father ever since, who decided to watch him die to be sure, that he was dead.