The overall harmony of Equestria could be disrupted. Twilight is often at the center of maintaining balance. Her absence might lead to small problems turning into big ones. Other ponies might start to panic, and the different pony tribes could have more difficulties working together without Twilight's diplomatic skills.
Spike would be heartbroken. He's like Twilight's little brother. He depends on her for guidance and love. If she runs away, he might try to find her on his own and in the process, grow up a bit as he faces challenges alone. He could also feel abandoned and struggle with his own self - worth.
It could make Batman more determined to find him. Batman would be worried about his safety and would start an intense search. He might also feel guilty, thinking that he could have done something to prevent Tim from running away.
For Aunt May, it would be a huge shock. She has already lost so much in her life, and Peter running away would make her feel like she has failed in some way as a guardian. She would probably be constantly looking out the window, hoping to see him come back home. Also, the villains in the story could see his absence as an opportunity. They might become more bold and start causing more chaos in the city, knowing that Spider - Man is not around to stop them.
His friends will surely be worried. They might start looking for him everywhere, feeling sad and confused about why he left. For his closest friends, it could be a very emotional time as they fear for his safety.
One possible reason could be that she feels overwhelmed by her responsibilities. In the world of Equestria, Twilight has a lot on her plate, like studying magic, taking care of Spike, and helping her friends. In fanfiction, the writer might explore the idea that she just needs a break from it all and runs away to find some peace.
It could cause a sense of loss. Harry is a symbol of hope for the wizarding community. His running away might make some people feel abandoned.
For her family, it could be a shock. Her parents might feel sad and regretful that they didn't have a closer relationship with her so that she could confide in them. Her siblings might also be affected, perhaps feeling a sense of loss or confusion.
It could make them realize how much they've taken her for granted. They might have been so focused on their gifts and their own roles that they didn't notice Mirabel's pain.
His friends like Hermione and Ron would be deeply affected. They might feel abandoned at first. Hermione, being the logical one, would understand his reasons but still miss him terribly. Ron would probably be more vocal about his sadness and might even try to convince Harry to come back.
For Harry, it could be a huge emotional blow. Sirius was like a father figure to him. His running away might make Harry feel abandoned again, and it could also fuel his determination to find out the truth and bring Sirius back.
It would cause a great deal of sadness. Molly Weasley, being a very family - oriented mother, would be heartbroken. She might constantly worry about Percy's well - being and feel like she failed as a mother. The younger Weasley siblings would also be affected. Ron, for instance, might feel confused and a bit betrayed, as Percy has always been a role model to some extent.