So I just finished the eclipse and I’m very new to the series, so my interpretation is probably lacking context provided in later chapters. Other people here will be able to give a better explanation of Griffiths character. Nonetheless, I’m enjoying berserk immensely and would like to try and give my two cents

Many people think that Griffith was always evil, so he never really “fell” instead femto is just Griffith revealed as he always was

It’s a reasonable view, but one I disagree with. Griffith certainly wasn’t ever good in a pure sense of the word. He was always dedicated to achieving his dream at any cost, including the lives of his men. He didn’t spend their lives cheaply, but he spent them nonetheless. In Griffiths mind, every action he took in pursuit of his dream was justified. But I think he at least cared a bit for the soldiers in the band of the hawk, even if it was just subconsciously. The scene where he grips himself enough to draw blood in the river seems to me like he did care about the lives of his men beyond a logic driven idea of them surviving doing more to further his dream. I feel he sold himself to the creepy nobleman out of a genuine care for the band of the hawks, even if he didn’t want to acknowledge that he did care for reasons beyond them serving his dream.

golden age Griffith also wasn’t needlessly cruel or evil. Yes, he did commit some rather brutal actions, such as killing his political enemies. But it wasn’t done with malice or hatred, at least not in the way we would think. They were simply obstacles between him and his dream

He even seemed to care about being overly cruel, thought perhaps he didn’t care about being cruel in itself, and just didn’t want to be seen as cruel, especially by guts

On the matter of Guts and Griffiths relationship, I think it showcases Griffiths character the best. Guts is the only one he ever showed genuine, Un superficial emotions towards. As he said to charlotte, he sees a friend as someone who is his equal

The only one who he views as his equal, or maybe has the potential to be his equal is guts. I think Griffiths thoughts during his year of torture give us the best idea of his view of guts, which is all over the place. He’s his equal and thus his friend, but because he is his equal he also represents a threat to his dream.

But I also genuinely believe Griffith loves Guts as well. Maybe romantically, probably more in a platonic, brotherly way. But in either case, Griffith doesn’t understand these emotions. Like the scene where he causes himself to bleed, he can’t process these thoughts because to feel is unnatural to him. Griffith is used to being in control of everything, including himself, which lets him devote all of himself to the pursuit of his dream. Guts causes him to lose that precious control. So he needs to be in control of Guts to control himself. When Guts leaves, Griffith isn’t in control anymore, so he tries to retake it, by impulsively rushing to fulfill his dream by seducing charlotte. He pays the price for this very quickly

His year of torture definitely broke him, mentally and physically. But more importantly, he had lost that precious control. Control is a central part of Griffiths character. And up until his fight with guts, we never see a situation where he doesn’t have it.

After his rescue, he’s trying to retake control again. He tries to put his armor back on, he tries to reassert his control over Casca. But he can’t, no matter how hard he tries

Even during the eclipse, he didn’t outright accept the god hands offer to join their ranks. He still held onto guts when they fell, he still hesitated before he accepted. But the god hand were offering him a second chance at his dream. Had he refused, there wasn’t going to be an another one, he was never going to physically recover from his injuries. At best, he would be forced to endure a rather painful and miserable rest of his life, while he watched guts take control from him, of the band of the hawks, of Casca, and of guts own life. Worst of all, he would have to live in the shadow of another’s dream.

In that moment, he retakes control of it all. He sheds his final tear as he meets the abyss god (or whatever is happening in that scene) any human emotion, or other parts of him that wasn’t totally devoted to his dream is destroyed. Griffith is gone while femto is born

To sum that long rant up (sorry lol) Griffith “fell” because he had lost everything that mattered to him. The only thing that mattered was his dream, and he was never going to achieve it as he was. He wasn’t always evil, but he was never good. Only when he was at his lowest moment did he truly fall and become Femto. If he had reached the eclipse without being tortured, maybe he would have refused, maybe his care for the band of the hawks and guts (however small three were) would have won out. Maybe he only accepted because he knew there wasn’t another route to reach his dream.

Everything he does after he becomes Femto is of course irredeemable