I'm not entirely sure specifically about the 'Pretty Little Liars Original Sin Mouse Story'. It might be some sort of sub - plot within the 'Pretty Little Liars Original Sin' series that involves a mouse in some way, perhaps as a symbol or part of a mystery.
The main plot involves a group of girls being tormented by an unknown assailant, who seems to be out for revenge related to secrets from the past. There are mysteries surrounding their parents' past actions that are starting to resurface and impact the girls' present lives.
The original series was full of mystery, danger, and a lot of negative elements like blackmail and lies. In positive fanfiction, there's often more focus on the good in the characters. For example, instead of the Liars constantly being in fear of 'A', they are more focused on building their relationships and achieving their goals.
One popular theme is the relationships between the characters. Fans often explore the romantic relationships in more depth, like Ezra and Aria's relationship, and create different scenarios for them.
It depends on what you specifically mean. If there is a piece of writing that features Aria from 'Pretty Little Liars' and it's not an official part of the show's storyline, then it could be fanfiction. Fanfiction can range from simple short stories to complex multi - chapter works. Maybe someone was really inspired by Aria's character arc in the show and decided to create their own story, which would classify as fanfiction.
It's about a group of teenage girls who are constantly dealing with mysterious and threatening events. They have to uncover the truth behind all the lies and secrets.
I'm not entirely sure as I haven't read it in full. But generally, the 'Pretty Little Liars' series often involves mystery, secrets among a group of girls, and a lot of drama in a high - school - like setting.