The hair tie might be related to a prophecy. In the fanfiction's lore, there could be a prophecy that mentions a girl with a black hair tie on her wrist who will save the world. Felicity, unknowingly, is that girl and as the story progresses, she discovers her true destiny.
It could be a symbol of love. For example, her secret admirer gave it to her, and she wears it to keep that person close to her heart, even if she doesn't know who they are yet.
Perhaps the black hair tie is a reminder of a past love. Felicity is constantly haunted by the memories associated with it. She meets someone new in the fanfiction, and the presence of the hair tie creates a conflict as she tries to move on from her past while still holding onto this memento.
The hair tie could be a connection to her past. Maybe it was from a special event or person. For example, it could be from a school event where she had a great time with friends. In the cave, it gives her a sense of normalcy and comfort in a strange environment.
It could be a simple fashion statement. Abby is known for her unique style, and the hair tie on her wrist might just be another part of that.
Perhaps it represents a connection to a past event. For example, she wore it during an important moment and now it's a reminder. In a fanfiction set in a post - apocalyptic world, it could be a memento from before the disaster.
In fanfiction, a black hair tie on the wrist could symbolize a connection to a particular character. Maybe it was given by a love interest, and the character wears it as a reminder of that person. It could also be a sign of a secret society or group within the fanfiction world, where the black hair tie is a form of identification.
Maybe it's a memento. In fanfiction, it could be from a special event or person. For example, perhaps it was given to her by Rory during one of their study - filled nights. It represents their friendship and all the shared experiences they've had while pouring over books and notes.
In fanfiction, the hair tie on the wrist could symbolize the trainer's connection to a certain Pokemon. For example, if they have a Pokemon that likes to play with the hair tie, it shows a bond between them. It could also be a sign of the trainer's preparedness. They are always ready for any situation, whether it's to keep their hair out of their face or to use the hair tie for some other creative purpose in their adventures.
It could be a simple fashion statement. Beth might just like the look of the black hair tie on her wrist, like it adds a certain edginess to her appearance.
It could be a symbol of love. Maybe it was from a romantic interest and every time she looks at it, she is reminded of their shared moments. For example, if it was a gift from a first love, it would carry all the emotions of that relationship like the butterflies in the stomach, the first kiss etc.