These aren't 'set in stone', but think about some of these:
1. Someone who is the complete opposite of the protagonist
Making a character in a more realistic setting who is, at first glance, completely different from your protagonist can really set interesting scenes. Having opposite characters, while people tend to say 'opposites attract', I'd rather say 'opposites oppose'. For example, for me, I would always despise people who talked too much in my classroom and thought they were funny for goofing around. I was the typical quiet type who was too busy writing and drawing in her notebook than the one who was more vocal in her classroom. Therefore, as you can tell, I sort of had a mental grudge with those sorts of people.
Obviously, my story actually sets up a more conflict-creator, or someone who isn't really a "bad guy", but rather someone who's goals (goofing around and playing in the classroom) definitely contradicts my own (sitting and being quiet).
Now, think about your protagonist. It seems that your character is the trouble-maker type. Always cutting up fights and not listening to authority. Now, if you want to make an antagonist who is really just the total opposite of your character, you could have them be seemingly perfect. Think of them as... Dolores Umbridge. At least in the movies, she seems to think of herself as the kindest, sweetest woman at first glance. But there's always something off about her. Perhaps your antagonist could have similar elements; a perfect person, perhaps too perfect, that makes your character feel as if there's something off. Whether that 'something off' is a conflicting ability, working for an organization, or just plain annoying is up to you.
2. Make them have more power
Maybe your character isn't the one to hate those with an opposite personality than theirs. That's fine! Considering she had the ability to manipulate lightning due to her gray eye, then I would say make this character have an ability similar to hers. Perhaps it could be a force that stops lightning, or maybe just a more powerful force altogether.
3. Make the protagonist the "good guy" in this situation
I say this one because your character isn't necessarily the best child I've heard of. Perhaps she thinks that what she's doing is actually right, even if it's morally wrong, and the antagonist is the one that's doing what's morally right. There's something about this trope that makes me appreciate it. It allows you to see a moral gray area, and this may work best for your character.
However, these are subjective. There are plenty of other ways, these are just some I thought of. Perhaps you can combine them, or not use them at all. This is your story, after all. Hopefully, I offered some insight that can help you out.