Forgiveness is not a sign of strength. It is an indication of a lack of conviction. Vengeance is not a sign of strength either. It is simply an indication of one's lack of creativity. "Fucking hell, he slapped me! Fucking! I'll slap him!". See what I mean? A severe lack of creativity.
Why is the Godfather such a great movie?
Besides the fact that Copolla is a magician working with two demi-gods (Al Pacino and Marlon Brando), the theme of the movie is gratification of whatever kind, bound by pragmatism. The movie doesn't pander. At no point does it slip it's hands into your pants and tries giving you a boner. It undresses in the most natural way.
It's why Al Pacino seems so real. Because at no point through the series does he make a decision to make you feel better about the world. He finds out about the fact that the mole from within his organization was his brother. Unlike most stories, where he'd forgive him or go after him, he does neither. He proves himself strong enough to be indifferent. You can feel the one million mutinies in his body, the many revolts amongst his many sensations, when he takes Fredo's face in his hands, with a strange conviction and kisses him with the kind of spite that only a brother can warrant, he looks into Fredo's eyes and expresses himself as simply as he can, "I know it was you Fredo, you broke my heart". Fredo eventually has to die. Not because of vendetta or karma. He has to die because of the principle of causality. He has to die because a system has to work and he isn't strong enough to let the system sacrifice someone else or change the system. He has to die because, that is what happens to the traitors when a plan to de-throne the Emperor fails. It doesn't matter who you are. Brother, lover, friend. The Emperor is the emperor before being any of these things. And if precedent, convention and causality call for death, a dispassionate death, one even without a simple motivation of vengeance, so be it.
You see what this system of forgiveness doesn't take into account is the fact that a mistake is accidental. A mistake can be forgiven. But a plot to de-throne the Emperor, isn't a mistake. It's a bad decision. And by the principal of causality all bad decisions must live through their consequence, "one ill turn deserves another". I'm only writing this because of the astonishing number of people who don't understand the difference between 'a bad decision' and a mistake. Because of the number of people who've tried to teach me the virtues of forgiveness. People have to go long distances to earn forgiveness. Earn being an important verb. I hate it when 'forgive' becomes the verb. Forgiveness must be earned, not gotten. It's hard to earn forgiveness. Judas had to hang himself.