

The Mirror Monster might have been drawn to the humpback girl because of her fears and potential abilities which could be used to ensure its freedom. In the beginning of the comic, the children state there are stories about a monster within the abandoned building, leaving the speculation that the towns people might have attempted to prevent anyone from potentially freeing the Mirror Monster by warning them of the dangers hiding in the building. This is supported by the mirrors ability to trap whatever is thrown into them, the boy who got strong was dragged into one of the mirrors but was unable to escape even after the Mirror Monster disappeared. Contrary, it's also speculated the Mirror Monster might have never been the humpback girl's creation but was instead a monster which had been imprisoned within the mirrors themselves by the towns people.The mirrors she and the children found may have the ability to bring to life a persons deepest desires as well as their greatest fears. It's speculated that the Mirror Monster was created from the humpback girl's fear of monsters.The children who had promised to return for the humpback girl near the end of the comic might have never returned because they were killed by the Mirror Monster who had now been unleashed onto the whole town. This is supported by the mirrors ability to transfer whatever is reflected in them onto the real world. Because the children are unaware if the Mirror Monster had perished, it's speculated that the Mirror Monster may still be alive but had now been freed from the mirrors world. When the humpback girl and the other children break one of the mirrors the Mirror Monster appeared in, the Mirror Monster is no longer shown within the other mirrors in the room. Implying the town they lived in might have always been aware of the dangers within the abandoned building and had attempted to warn the children of its terrors through stories alone, it is unknown what these stories told, but it's suspected the adults of the town had attempted to leave the mirrors untouched in order to prevent whatever could be unleashed from them from hurting anyone else.

According to the boy who got tall and the humpback girl, there are terrifying stories surrounding the very building where they would inevitably face the Mirror Monster.
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He is seen teleporting his tentacles out of his mirror reality and even moving them from mirror to mirror.
