In some fanfictions, Hermione's elemental powers might be linked to her intelligence. For example, she studies ancient magic texts and unlocks the knowledge of how to manipulate water elements. This could lead to her using water to put out fires in Hogwarts or even creating water bridges to cross difficult terrains.
One common power she might be given is telekinesis. This allows her to move objects with her mind, which could be really useful in various situations in the fanfiction world, like during battles or when she needs to retrieve something out of reach. Another power could be enhanced intelligence, beyond what she already has in the original story. This would make her an even greater force to be reckoned with when it comes to solving complex magical problems or outwitting her enemies.
It would change the story significantly. Hermione could use her elemental powers to solve problems more quickly. For instance, if there was a locked door, she could use air element to blow it open instead of using a spell.
If she has a powerful combat - related power, like super - strength or the ability to shoot powerful spells without a wand, it might make some characters in the wizarding world jealous. This could lead to some characters trying to undermine her or isolate her. However, her true friends like Harry and Luna would likely support her and be in awe of her new abilities, which would deepen their friendship.
It could deepen her relationships. Her friends would see her in a new light. Ron and Harry might be in awe of her at first. But then, they would need to adapt to this new Hermione. She would have to learn to balance her new power within their group dynamic. Maybe she would feel isolated at times because she's the only one with this power, but it could also bring them closer as they work together to help her master it.
Maybe the child has the power of mind control. Hermione is known for her strong mind and intelligence. Her child could inherit a more extreme version of this, being able to control the minds of others. This could be a very dangerous or useful power depending on how the child is raised and what their intentions are.
One plot idea could be that Hermione discovers her ice powers during a dangerous adventure in a frozen tundra. She has to learn to control them quickly to save her friends from an ice - bound monster. Another could be that she uses her ice powers to create a magical ice fortress to protect Hogwarts from an impending dark magic attack. Or perhaps she is the only one with ice powers in a world where everyone else has fire - based magic, and she has to face discrimination until she proves the value of her unique powers.
Well, in some fanfictions, Percy might have the power of enhanced underwater communication. He could talk to not just regular sea creatures but also mythical ones that are usually hard to reach. For example, he might be able to have a full - fledged conversation with a kraken.
In this fanfiction, the prototype powers could be something like an early form of chakra manipulation that is different from the traditional Naruto world's chakra use. It might be more raw and unrefined, with the potential for new and unique jutsu.
Her relationship with Harry might become more of a protector - protected dynamic. Harry would be in awe of her new powers and might rely on her more in dangerous situations. With Ron, there could be some jealousy at first as he might feel left out. But eventually, he'd see the value of her powers and they'd become closer in a different way. And with the professors, they would either be intrigued and want to study her powers or be a bit cautious in case the powers got out of control.