The most important dialog in the Godfather series (and for this I only include The Godfather parts I and II) occurs in Godfather II. It is a conversation between Michael and his mother in which Michael asks her whether it is possible to lose his family:
MICHAEL
Tell me something, Ma. What did Papa think -- deep in his heart? He was being strong -- strong for his family. But by being strong for his family -- could he -- lose it?
MAMA
You're thinking about your wife -- about the baby you lost. But you and your wife can always have another baby.
MICHAEL
No, I meant -- lose his family.
MAMA
but you can never lose your family.
MICHAEL
Times are changing.
The Godfather is the story of a man fighting to save his family and losing it in the process. The tragedy of Michael Corleone is that he loses his family because he fights for it; or, rather, because of the way he fights for it. For Michael chooses to fight for his family by inverting the moral order of the universe. He treats his family as the highest good for which everything else must be sacrificed. He puts it before his country and even before God. In the end, he suffers the fate that befalls those who put the lower before the higher: Not only does he lose the higher, but he loses the lower as well. He loses his family. The tragic irony is that Michael himself is the means of the destruction of his family. The Godfather I ends with Michael ordering the execution of his brother in law; The Godfather II ends with Michael ordering the execution of his own brother.
The first Godfather film opens with the famous wedding scene at which we see Michael dressed in his Marine Corps uniform. Michael’s uniform symbolizes his submission to the moral order of the universe. He joined the Marine Corps out of duty to his country and in defiance of his father’s wishes. He puts God and country before family. His brother Sonny cannot understand Michael’s decision; Michael fights for “strangers.” Sonny is the pure and unreflective Mafia soldier. He cannot imagine any other system of values than the Mafia system. Michael can imagine both the Mafia scale of values and the natural (that is, true) scale of values and choose between them.
The crucial, and ultimately tragic, decision for Michael comes when he visits his father in the hospital, Vito barely having survived an assassination attempt. During the visit Michael notices that the hospital is nearly empty of attendants and, most disturbingly, of the guards assigned to protect his father. Demonstrating the resourcefulness, courage and coolness under pressure that are among his many virtues, Michael saves his father from certain death by bluffing a squad of “buttonmen” (assassins) who arrive at the hospital. Michael whispers to his father that “I am with you now, Pop”, and Vito smiles in response. But if Vito knew what Michael really meant, he would not have smiled. Vito planned for Michael to succeed legitimately by becoming a Senator or a Governor; he hoped to preserve him from the criminal side of the family so he could lead the family out of the shadows and into the light. But what Michael meant by “I am with you now” is that he has accepted the scale of values by which the Godfather lives. He is no longer the Marine killing under orders from legitimate authority; he has taken the prerogative of dealing life and death into his own hands. Like his father, Michael is now prepared to commit murder in defense of his family, a commitment he will shortly fulfill by killing a Mafia enemy and a police captain in a restaurant. When Vito is later brought home and learns of the murder, he weeps and orders his son from his room. Vito’s worst nightmare has been materialized. Michael has done more than be with him; he is becoming him.
Michael’s tragic flaw is, of course, pride, the most dangerous vice and the one to which a man of his many talents is particularly vulnerable. Michael takes the privilege of dealing life and death into his own hands because he believes he possesses the wisdom to wield it, and the virtue to prevent it getting the better of him. And, for a time, he is successful. His assassinations of Sollozzo and the police captain are tactical masterpieces and strategically shrewd. But just as Tolkien’s One Ring provides great power but inevitably corrupts those who wield it, so the man who takes up murder as a weapon is inevitably corrupted. Michael becomes hard, cold, isolated and increasingly merciless. At the start of the film, he is honest with Kay about the true nature of his family. He tells her a story, a story he reassures her is true, of Luca Brasi threatening to blow a man’s brains out on orders from Don Corleone. “That’s my family, Kay, it’s not me.” But when he embraces the Don’s way of life, it does become him, and along with murder, Michael must adopt a life of fundamental dishonesty with respect to Kay. This dishonesty, among other things, makes their relationship, as Kay later says, “unholy and evil.”
Although Kay comes to recognize the evil nature of her marriage to Michael, her tragedy is that she has already become fatally corrupted through her association with him. Her answer to Michael is an attempt to put an end to the unholy tradition of the Corleone family (this “Sicilian thing” in Kay’s words) by aborting Michael’s son; in other words, she fights Michael by adopting the same culture of death he has accepted. She is right that Michael can never forgive her for this, but doesn’t quite understand why. It isn’t because Michael has a problem with abortion and murder per se (obviously.) This would matter if Michael recognized some higher authority beyond himself and Kay. But for Michael there is no higher authority; he is the final authority on life and death, as ratified by the brutal fact that he is alive and his enemies are dead. Membership in the “family” is contingent on the recognition of his authority; the only sin Michael is not prepared to forgive is betrayal of the family, defined as dealing in death without authorization from Michael. In the Godfather II, there is a moment when Kay sees Michael while dropping off the children; it is obvious from her expression that she hopes for a reconciliation. Her desire for a reconciliation is evidence of her own corruption, for she wishes to be reconciled with a man she knows has an ongoing commitment to murder. Michael silently closes the door in her face; for having become a dealer in death herself, she can henceforth only be his rival and never his wife.
Kay manages to escape her association with Michael with her life, but Michael’s brother Fredo is not so lucky. Fredo is in many ways a more sympathetic character than Kay. Kay is intelligent and perceptive, but degrades herself both by attempting to fight Michael through abortion, and later attempting to take it back through a reconciliation. Michael can have nothing but contempt for her. Fredo, Michael perceptively tells Tom Hagen, is stupid and weak but he has a good heart. Alone among the family he congratulated Michael on his enlistment in the Marine Corps. Knowing nothing else, Fredo attempts to lead the life of a Mafioso but is humiliated at every turn. He fails miserably to protect his father in an assassination attempt and cannot manage his own wife on the dance floor after she publicly insults him. His pride hurt, Fredo tries to conduct some Mafia business of his own independently from Michael’s supervision, with predictable results. Fredo is exploited by some of the family’s enemies with nearly fatal consequences for Michael. But at no point is there any evidence that Fredo actively participates in a murder or a murder conspiracy. When we see him with the family it is either in standard family activities like supper or business meetings concerning things like his future in Las Vegas. He is absent when murder conspiracies are discussed. Now the reason for this is, at least in part, that Fredo has nothing to contribute to such meetings and may even pose a security threat through the possibility that he may inadvertently reveal sensitive information to the wrong people (something he actually does when he attempts to strike out on his own.) It nonetheless remains that alone among the principle characters, including Kay, he is innocent of the attempt to actively and personally use violence as a solution to his problems. His difficulties on the dance floor with his wife are evidence that he may be constitutionally incapable of violence. But beyond that, he simply doesn't think in those terms. This is what Michael means when he says Fredo has a good heart. He is susceptible to exploitation not only because of his stupidity, but because of his tendency to assume innocence in the motives of others, a reflection of his own innocent motives.
Fredo's pride leads him to foolishly strike out on his own, and for a time he rejects Michael's offers of a reconciliation. It is only after Fredo hits bottom, and admits that information he gave to Hyman Roth led to an assassination attempt on Michael, that he comes back to Michael in the form of the Prodigal Son. Unfortunately, Michael is no longer the forgiving father.
By this point, near the end of the Godfather II, Michael has degenerated to the point that forgiveness is beyond him. There is little more than paranoia in his heart. Fredo, whose sins were sins of weakness (the type least dangerous to the soul), accepts his nature and is content to live out his life as a kindly uncle. If there is anything left worth preserving in the family, it is Fredo, who maintains a measure of innocence. He poses no more danger to Michael and is not really deserving of the execution Michael orders, for although he consciously disobeyed Michael as the head of the family, he never attempted to betray him as did Kay and Tessio. But Michael's soul is now fully embraced by the murderous spirit he adopted with siding with his father, and he kills the last good thing in his family by "being strong for it." We last see Fredo praying the Hail Mary as a Corleone soldier puts a bullet in the back of his head.

