I'm not entirely sure as I haven't read it specifically. But generally, a novel about 'drifters' might be about people who are constantly on the move, perhaps exploring different places, cultures, or just living a nomadic lifestyle.
The 'the drifters girl' story is likely about a girl who has some connection to the Drifters. Maybe she's a fan, or perhaps she has a personal journey intertwined with the group in some way. Without more specific information, it's hard to say exactly.
A great drifters fanfiction could explore the backstories of the characters in more depth. Maybe it delves into how they became the way they are. It could show their early training, their first encounters with the forces that led them to be drifters, and the relationships they had before their drifting adventures started. This would give readers a better understanding of the characters and make their actions in the main story more meaningful.
One common theme is self - discovery. The original characters often find out more about themselves and their abilities in the strange world of drifters. For example, they might learn that they have a special power they never knew about before.
I'm not sure exactly who the characters are without reading it. But they are probably drifters of different backgrounds. Maybe some are young people seeking adventure, and others could be those who have lost their homes for various reasons.