What makes Griffith so utterly delicious as a villain is his complexity and how (most) of his actions are "justified", even from the reader's point of view. Long story short: Griffith showed repeatedly throughout the Golden Age flashback the stress losing his loyal followers had on him, which caused him to slowly spiral into more questionable actions as his desperation to honor the lives of the living and dead weighed upon him. Prior to the Eclipse, this is best exemplified when he prostituted himself to Gennon after staring at the corpse of a little boy for who god knows how long. Griffith had to keep himself in denial about what he truly feels, otherwise he'd collapse, which he eventually did when Guts left.
This is his principle argument when he countered Guts' accusation of betrayal after the Mock Eclipse. In his mind, he did wish for their deaths, but there was no betrayal. The true betrayal would have been to give up, causing all the sacrifices contributed to Griffith's cause to be for naught, especially after the torture he had endured for the past year. In other words, to betray his dream was to betray every person who had ever fought for Griffith, which is one of his major reasons for accepting the God Hand's offer. In Griffith's mind, every life counts. During the Eclipse, the Band of the Hawk was granted the "honor" of being the fuel that bestowed him godlike powers in order to make his dream a reality. During the Mock Eclipse, the peasants were granted the "honor" of being the fuel that bestowed him the flesh he needed in order to carry out the wishes of the both the dead and the living. During the Kushan Invasion, the invaders, specifically Ganishka, were granted the "honor" of being the fuel that bestowed him the means to merge the Astral World with the Material World in order to grant mankind's wish of a harsh utopia, Falconia. Griffith's actions have undeniably benefited mankind as a whole, but what makes him so twisted and villainous is how he accomplishes his goal, by piling mountain of corpses wherever he goes. So many people have died and this is what makes Griffith so dangerous. He doesn't know when to stop because he is blinded by the dangers his ambition poses to others, including himself.
On the matter with raping Casca and forcing Guts to watch is "justified" in Griffith's mind. Casca and Guts "betrayed" him. In reality, it isn't true since it was done out of 100% pure spite, but this is how Griffith perceives the situation. This is probably the main reason Griffith lost interest in harming Guts and Casca after ch. 180. They're not a threat to his plans and leaving them alive as they are in their current states is a more fitting punishment than simply killing them, hence the "Nyah! Nyah!" stunt Griffith pulled when he left Guts behind in the snow, a callback to what Guts did Griffith several years prior. His development combined with wanting to get his comeuppance is what makes him a great villain.
This point isn't a reply to yours. Just my personal thoughts: Griffith is a character that is defined by his ambition. He is an inveterate dreamer and his vehement desire was always to aim towards the lofty apex of the castle spires. This was shown through his pure pursuit of ideals to grasp his dream. And let's be honest with ourselves, a man is nothing without his dreams. We need dreams, ideals and pursuits to complete our existence. Give it purpose. To assume that dreams aren't selfish is a self-serving mentality. It isn't real. When one person acquires a dream somewhere, he has crushed the dream of many to acquire the same thing. That is how it is; one dream is achieved by ending many. That is the truth of the matter.
We have seen him so emotionally invested in his ideals that he intentionally distanced himself from his comrades after witnessing the untimely demise of a child amongst his troops; a mere boy. It was more of a moment of self-pity he projected onto the child when he stated that, "he must have had a dream as well." He realized it then that that could be him in his place; death ending his dream; ending everything for him. Which is why he chooses to solicit and gains the funds to climb out of that rut of consistent losses of men; setbacks thwarting his dream. It was a decision to gain heights and spread his wings wide; the same reference when he fell so far down after his night with the naive princess.
Griffith was the man who was meant to achieve his dream by standing over the bodies of his comrades. It was always meant to be this way, as each victory was forged in the blood of his fallen comrades. He gained rank through deaths. He was a leader. He was always meant to lead, not chase. Which is why we find the Band of the Hawk willingly claiming to sacrifice theirs so that Griffith can literally soar high like the hawk he was always meant to be. Once that dream, that ego, that passion, that control melded together firmly over the years, it made Griffith the man he was; an admirer of dreams; a pursuer of his dream of a castle. It defined him till the moment he was not reunited with the Behelit. He was always extraordinary like the unique Behelit he was meant to find. An overman amongst men. His transcendence to Femto was so fitting to fully realize these facets of him. His humanity held him back.
He considered Guts a friend. However, the intentional distancing and the ideals molded him into a man who considered people around him more of helping hands, pieces on the chessboard with him being the finest one; a king. Once he is humiliated by Guts, it dawns on him that he cannot control the tides of fates as perfectly as he had hoped. That loss of control and the idea that he will not be able to maintain hold over all his troops, sends him cruelly spiraling down, where he makes one terrible mistake after another. The quick decision to remedy his bruised ego through a hasty sexual encounter costs him so much more than he bargained for.
It would be difficult to plumb the depths of his despair when he was completely deconstructed as a man after the inhuman torture. To state that he was left as a shell of his former self is putting it so lightly. The man was emasculated, humiliated and dethroned out of the safe haven of his dream castle. He was no longer the beautiful, clever-minded general all admired ... but a man to be pitied. I don't think there could have been any greater cruelty. Once given a choice to end his life or a life of a pitiful invalid ... or grasp the chance to become a god, he chose what everyone would; a chance to live the dream. I will never belittle Griffith to choose what he did; it came so naturally to him. It was a human moment to end his life and accept the God's Hands proposal to transcend reality. Even if you remove the factors leading him up to that moment, it would be impossible to deny such an opportunity; a chance to become a god! Be the king of causality and fates. It's an impossible dream, an awesome power! The temptation to acquire it will triumph over everything.
The points that I tend to deviate from are those where people assume Femto to be evil. Are GodHands really evil? There is no such thing as an absolute evil. Evil is fueled by perspective. Griffith has transcended perspectives. He is no longer a human. He is no longer bound by the factors of "manufactured" morality. Yes, morality is always manufactured. It is not something absolute; it's always destined to reach an obsolete status one way or another, given its changing nature with the shifting winds of societal axioms. Can we really call God in the three well-known orthodox religions as evil when he decimated civilizations, and still does if one counts the idea of "fate" in religion?
I will consider Femto as no different. He leaves mountains of corpses and decides fates. To him that Utopia is well-earned on the pile of corpses. Just as Heaven is a well-earned paradise over the dreary pits of hell that is a brimful of the absolutes of human despairs. The promised lands are always built on corpses and crushing dreams, which makes Griffith so raw and realistic even as a lesser god. As Femto, Griffith transcended humanity, he transcended evil, he transcended good ... he became an axiom of hope and despair himself; a true god! He became the very ideal he chased after. Femto is nothing more than a personification of his own ideologies, only far more exalted, more detached and more removed from reality. He's unreal and real at the same time.
I would consider Femto as a complete reconstruction of Griffith. Not just physically (interestingly, he has gone through two rebirths since his death as Griffith; Femto and the White Hawk God who created Falconia), but spiritually and thematically as well. At his core, Femto is an incorporeal being. He sees things in the shades of fates and causality. He isn't a part of them like humanity or as Griffith was. He's beyond that. To judge him on the merits of humanity makes little sense as he doesn't even lie on the shallow stratum of reality, but the deep stratum. His rebirth simply gives him a make-belief flesh to reside amongst humans and make his dream a reality within the bounds of the laws of the corporeal stratum. That doesn't make him any less of a god. He's simply a god with a fleshy garb. Thus, every single act from Griffith is justifiable one way or another, and that is what makes him highly complex.
I disagree with the rape argument people have as well. Why would Femto desire to spite Guts and Caska? I found that scene to be utterly pointless and a stuff of base titillation. If I was supposed to loathe Griffith in any manner, then I can assure people that it never crossed my mind. As to associate notions of morality with gods and hell is such an insufferably absurd and terribly narrow-minded view to begin with that throws any semblance of context away altogether.
The scene and the sheer stupidity of Casca surviving purely on grounds of the perversions of demons were absolutely laughable ... and she has been baselessly comical since then. She was never a decent character to begin with. It was not until his rebirth and the facts surrounding it resurfaced that I finally understood that he only wanted to corrupt the child to use it as a vessel, albeit it is another grand Deux Ex Machina in Guts' favour; one of the many this character so shamelessly keels over on. There is nothing more to it than that. To give it more meaning would mean that the GodHands have corporeal inclinations; traits of the flesh, and that would go everything against what we have seen.
I have also never understood why Griffith has not killed in a manner fitting to his character. The Deus Ex Machina pile up (and it's one after another) since the troll arc to shield Guts' highly ludicrous character have been a stuff of horrid writings. Him disregarding their existence has a lot more to do with poor writing than any deep thematic value. I really hope this plot recovers soon, as beyond Griffith, there isn't much salvageable material there and Guts' quest for vengeance is as nonsensical as Casca's memory loss that has lasted over a decade worth of chapters ...
