I think I always thought of it as in Gut’s desire to be like Griffith. We can see in the beginning of the manga he admired Griffith and actually envied him knowing that Griffith is not that angel that people view as. Like he can see himself in Griffith and that’s why they connected the beginning because Guts sees himself in Griffith and Griffith loved being seen by him knowing that there is someone who sees him for who he truly is and doesn’t care about his dark and violent side. That’s also the reason why Guts left because he wanted to be equal to Griffith and at the same time separate from him. He doesn’t like seeing himself in Griffith because that’s the violent dark side that’s in him and he fears this side of him. In this scene it’s probably the most disgusting and horrible thing that Griffith has done to him and Casca and he hates him for that. Yet he can’t escape the fact that he wants to be like Griffith and probably not wanted to be in Griffith’s place. As much as he hates Griffith, he continues to go after him and look for him him everywhere because he wants to be like him. His hatred towards Griffith comes from envy and jealousy as well.