A maester who discovers the existence of the giantess could be the main character. He would be intrigued by her and study her. His knowledge and curiosity could lead to him being the one to bridge the gap between the giantess and the rest of Westeros. He could write about her in his chronicles, and his actions would determine whether the giantess is seen as a friend or foe to the kingdoms.
One possible plot could be that a giantess emerges from the far North, beyond the Wall. She could be a remnant of an ancient race. The characters in the Game of Thrones world might initially see her as a threat. For example, the Night's Watch could fear she is allied with the White Walkers. But as the story unfolds, it turns out she has her own motives. Maybe she is seeking a lost relic that was stolen from her kind long ago. And she might form an unexpected alliance with a group of outcasts in Westeros to achieve her goal.
It could be Meg. Since she's often the outcast in the show, turning her into a giantess could be an interesting twist. It would give her a new - and very literal - form of power and attention that she doesn't usually get in the show.
A 'giantess cuckold story' typically involves a fictional scenario where there is a giantess character in a relationship dynamic that may involve elements similar to the concept of cuckoldry in some way. However, it's often a very niche and specific type of fictional or fantastical narrative.
No. Popular stories usually have themes that are more widely understood and appealing. 'Giantess cuckold stories' are extremely niche. They involve rather complex and not - so - common relationship dynamics along with the very specific idea of a giantess. Most people are not drawn to such stories as they are far from the typical story elements that are popular in mainstream literature, movies or other forms of media.
Giantess girl comics are known for their imaginative scenarios. They might feature giantesses interacting with normal-sized people in unexpected ways. The themes can range from adventure to romance, depending on the creator's vision.