Are you asking why a device with no feelings or personal life experience can’t create realistic dialogue when prompted to create something based on dialogue from comics and fanfic? Comics which barely explain context with words (since they use images)? Have you noticed how over the top, melodramatic, stylized and unrealistic dialogues are in so many comics, superhero ones in particular? Fanfic isn’t that much better. Of course there are some with good writing but the vast majority is mediocre at best and cringe at worst.

I’m surprised the LLM could come up with something narratively cohesive to begin with