The 'Death of a Superhero Novel' might explore various themes. It could be about the end of the superhero archetype in literature. Maybe it shows how the concept of a superhero has become tired or has outlived its relevance in the context of novels. It might also deal with the death of a particular superhero within the story, which could symbolize the end of an era or a shift in values.
One possible plotline could be the physical death of the main superhero character due to a powerful villain. This would lead to chaos in the world that the superhero once protected, and the remaining characters would have to deal with the aftermath.
I haven't actually read this specific 'piccolo and gohan lemon fanfiction', but generally, in fanfictions involving these two characters, it might explore their relationship in unique ways. It could be about their friendship evolving, or perhaps their teamwork in new and unimagined scenarios within the Dragon Ball universe.
A major theme is identity. Since she is a female version of Piccolo, she has to come to terms with who she is compared to the original Piccolo. Family also plays a role. In some fanfictions, she might be searching for her family or creating a new family of her own. Additionally, the theme of good vs. evil is common, as she battles against various villains.
I'm not that familiar with the specific 'Brian Piccolo Thanksgiving Day story'. Maybe it could be about how he spent the Thanksgiving Day with his family, sharing a big meal and giving thanks. It might also involve some special traditions he had on that day.
I'm not entirely sure which specific 'piccolo x gohan lemon fanfic' you're referring to. But generally, if it's a fan - made story, it might explore unique relationships and character developments. It could potentially show how Piccolo and Gohan interact in a different way than in the original series, perhaps delving into their friendship or a more complex emotional bond.