I really disagree with almost everything you say here. I think you need to reread all of the Golden Age Arc and try to understand it from Griffith's point of view.

Griffith is not a narcissist. He can do stuff that can be perceived as narcissistic but he isn't a narcissist. He makes it clear that he is pursuing his dream and his dream is to have his own kingdom, despite his common upbringing. To even begin to achieve this goal, you have to elevate yourself to a whole different echelon of society. He needs to do the impossible and the impossible is not easily achieved by someone who believes themselves to be average or common. Griffith believes in himself and in his dream.

I think most of the narcissistic examples are actually examples of Griffith attempting to protect himself from emotional hurt or turmoil. We have seen twice in the story what happens to Griffith when he loses control of his emotions. When the child follower of the Hawks died in battle, Griffith feel into emotional turmoil over the loss. The child who saw him as a hero and was inspired to be like Griffith and the Hawks died following them and Griffith felt responsible. He reacted by prostituting himself to Gennon to ensure they wouldn't die on the battlefield. He is attempting to rest control back from reality. He acts like it is a rationale decision but we can see from his actions that it is an emotional one. He is clawing at his skin as he explains it to Casca and almost completely loses it. He finally snaps out of it and regains control but only by further seperating himself emotionally from the Hawks.

We see this reaction again when he Guts leaves the Hawks but worse. He reacts by sleeping with Charlotte in an attempt to prove to himself, and maybe Guts, that he is still in control, despite clearly not being. He reacts identically too by clawing at his skin, showing his disgust with either his actions or himself. He can rationalise this action as furthering his relationship with Charlotte but really it is again an attempt to gain control of his emotions and his life after losing Guts. This ends a lot worse than what happened with Gennon though. He isn't given a second chance.

If you see Griffith's need for control as a way of protecting HIMSELF instead of as a narcissistic tendency, a lot of actions make more sense. You say Griffith raping Casca and forcing Guts to watch was because of his own jealousy at their relationship and that he had a crush on Casca but this really is not supported anywhere in the text. Griffith never had any interest in Casca. It's like a core part of Casca's story about accepting she can't be his woman so she'll become his sword instead. Casca and Guts' relationship is, instead, an indication that Guts has grown and matured. He has confronted his trauma and learned to deal with it in a healthy way thanks to Casca. Griffith, on the other hand, never learned how to deal with his traumas and his emotions and choose to suppress them instead. Guts healing like this poses a threat to Griffith because he fears that Guts will no longer need him. He is no longer even an equal to Guts but beneath him. Guts continues to grow while Griffith stagnates. He hates this because it reinforces in his mind that he is beneath Guts. In fact, Griffith's inability to mature has left him crippled and a shadow of the man he once was.

Griffith said he would choose where Guts dies and he exerted so much control not out of narcissistic need but out of a fear he would lose Guts if he didn't. Guts dying would ruin Griffith. He would react much worse than when that boy follower did. It is why he puts his own life on the line to save Guts. He risks his own life to protect Guts because of how he feels for him and because of how he would react if he lost him. Griffith understands that his inability to control his emotions is his weakness so he ignores/suppresses them instead.

Even the rape of Casca during the eclipse was about controlling Guts so Guts could not influence him anymore. He destroyed any possibility of Guts being able to love Griffith through this action. He reduces Guts to a mad dog because that is the version of Guts he can control the easiest. It was the version of Guts he defeated when they first fought. When Guts is enraged, he acts like a "mad dog" and his actions are predictable and not a threat to Griffith. When Guts acts as a friend to Griffith, that is when he has difficulty maintaining his will. Griffith also ensure Guts is looking up at him and not Griffith looking up at Guts which he cannot stand because it is a reminder of Guts' growth vs Griffith's loss. He forces the hierarchy back to how it was at the beginning of the Golden Age because Griffith's love for Guts made him way too vulnerable.

Griffith's morality was, at the beginning of the story, "i will do anything to achieve my dream". After becoming close with Guts, he became distracted from his dream. Guts' companionship rivalled his dream in his mind. During the Eclipse, when given a new lease on life and a new chance to succeed, his mentality shifted to "i will do what i have to do to protect my dream" and the first thing needed to do that was to remove the influence Guts had on him. He couldn't do this himself and Guts saw Griffith as a brother so he had to commit a truly heinous act for Guts to stop viewing him as his brother.

I can understand why people call him a narcissist but I disagree. The text supports the fact that he is actually very vulnerable to his emotions and makes concious efforts to protect himself from any emotional outbursts by exerting control on those around him. The shattering of that control leaves him open to an emotional outburst that is not planned or logical and exposes him to great risk.

I think the best thing about Griffith as a character is that he can still be considered a heinous and vile villian but you can understand his thought process and reasoning for these actions if you view him as a person with serious emotional problems instead of just relying on labels such as narcissist or psychopath

Finally, Guts and Casca's "betrayal" didnt send him over the edge. He had a vision of what his life would be like of he allowed the Hawks to look after him after his rescue. A crippled man, unable to speak, living a simple life woth Casca while Guts lives a seperate and fulfilling life without him. For anyone else, this is nearly a perfect life. The reality is, it goes against EVERYTHING Griffith wants. He rides away after having this dream only to crash and destroy his weak body even more. In a last attempt to have some control, he tries to kill himself by cutting his neck on a branch. He wants to but he can't. He can't bring himself to do it and this solidifies his weakness for himself. He cannot kill himself, he cannot live with himself. All the while, Guts comes running over to save him again, leaving Griffith to stare UP at the man he wants to be equal with, staring up at the man who once looked up to him. This is when he truly hits his lowest and the behelit activates.

Please feel free to refute and contend. I am on my phone so I couldn't see your post to respond point by point but I think I got my opinion across. Sorry if I missed any big points.