Perhaps Abuela believes that Mirabel's presence without a gift is somehow jinxing the family's magic. In the fanfiction, she might think that by imprisoning Mirabel, she can stop the negative effects she thinks Mirabel is causing. This could be related to some superstitious beliefs within the Encanto about the balance of magic and the role of each family member.
I'm not sure specifically as it could be any number of creative interpretations. It might be about a situation where Alma Madrigal blames Mirabel for something within the context of the fan - created story, perhaps related to the events or family dynamics in the Encanto universe.
The younger characters in Encanto like Antonio would be excited. He loves stories and new ideas, so Mirabel fanfiction would be like a new adventure for him. He might want to share it with his animal friends. And Dolores, with her ability to hear everything, might already know about the fanfiction. She could be either intrigued or a bit worried depending on how the fanfiction is being received by the rest of the village. If it's causing a stir, she might be concerned about the family's reputation, but if it's positive, she would likely be quietly supportive.
Maybe she feels left out in the family. In the Encanto story, Mirabel is the odd one out not having a special gift. This could make her feel so alone and unwanted that she decides to run away.
It could be someone who is jealous of Mirabel's potential. Maybe a relative who feels that Mirabel's new - found importance in the family (even if she doesn't fully realize it yet) threatens their own status. For instance, a cousin who was once favored but now sees Mirabel as a threat.
She could run into some trouble. Since she's on her own, she might get lost in the jungle outside the Encanto. Without the protection of the family's magic, she has to fend for herself. But this could also be a chance for her to grow stronger. She might find a small village where she starts to learn new skills, like farming or making clothes. Eventually, she could return to the Encanto with a new perspective and newfound abilities.
She could go to the mountains. The high peaks are often seen as a place of solitude and mystery in many stories. There, she might find a cave where she can hide and think about her life. It could also be a place where she discovers some long - forgotten magic that has been dormant for ages.
There are several places to look for this fanfiction. As mentioned, AO3 and FanFiction.net are well - known platforms. However, you could also check out some Encanto - focused fan communities on social media platforms like Tumblr or Reddit. Sometimes, fans will share links to their favorite fanfictions or even post their own work there. Additionally, there might be some smaller, more niche fanfiction sites that could have this particular story, but it might take a bit more digging to find them.
Another possibility is that she uses this time alone to reflect on her relationship with her family. She could come up with new ways to communicate and bond with them. Since she's always felt a bit like an outcast, this isolation might give her the clarity she needs to better understand how she fits into the family dynamic.