Since I haven't read it, I can't say for sure. But we know Gregor is likely a main character. There may be other characters like friends or foes that Gregor encounters in the story related to the snow - castles.
I'm not sure specifically as I haven't read it. It could be about a character named Gregor in a world of snow - castles, perhaps a fantasy setting where Gregor has adventures in or around these snow - castles.
The main character is Gregor. There are also other characters like the underground creatures he meets.
Since we don't know the exact story, it could be the kings themselves. They are likely the central figures.
I don't know for sure since I haven't read it. But it could be children who love building sand castles.
As I'm not aware of the 'Christopher Gregor story', it's difficult to define who he is. He might be a character who has certain goals or dreams in the story. Maybe he is a hero who overcomes difficulties, or perhaps he is just an average guy caught up in some interesting events.
An ancient curse or a malevolent spirit could act as the main antagonist in a more supernatural take on the 'castles family held hostage fanfic'. The family's castle could be built on an ancient burial ground or have some dark history. The spirit holds the family hostage within the castle, and the family has to figure out how to break the curse or exorcise the spirit to free themselves.
Well, the dragon would obviously be a main character in its own right. It could have its own personality and motives.
Boots is also quite popular. Her innocence and unique connection to the Underland make her an interesting character to write about. Fanfiction writers might show her developing special powers or having her own adventures separate from Gregor.
Snow and Hope Lemon are the main characters. Snow could be a character with a cool and calm demeanor, perhaps having some special powers like being able to control ice. Hope Lemon, on the other hand, might be a more optimistic and energetic character, always bringing positive vibes and having a unique ability like being able to heal with the power of lemon - scented energy.
Obviously, Jon Snow as a reborn dragon is the main character. But there could also be characters like Daenerys who might play an important role. She has her own connection with dragons, so her reaction to Jon's new form could be a significant part of the story.