I haven't come across a Chinese novel that is clearly centered around the phrase 'you have guts'. Chinese novels cover a wide range of themes, from love and family to war and adventure. While courage is a common trait in many novels, there may not be one that is so simply named or themed as 'you have guts'.
Guts is purely fictional. It's a concept or character that exists within the realm of imagination and creative storytelling rather than being based on reality.
I'm not sure which novel you're referring to because you didn't provide enough information. If you can tell me the name of the novel or the author, I will try my best to provide you with a complete version of the novel and try to avoid repetition.
Perhaps in this fanfic, Griffith has turned into something truly evil and a threat to the world Guts cares about. Guts, being the warrior he is, might feel it's his duty to put an end to Griffith to save others. Also, Guts could be driven by his own sense of justice. If Griffith has wronged innocent people, Guts may decide that killing him is the only way to set things right.