For some reason it won't let me post on Wattpad even though I have an account, so I'll leave feedback here <3 I used to work at the writing center in my school so sorry if it's a lot haha <3
This is a fantastic idea. Teens already have enough trouble trying to exist in the world around them as they grow and learn more, adding powers of elements on top of it just amplifies the difficulties of the world so everyone can relate. I love the unique names, they make the story distinguishable. It's not just "Lily" or "Claire", there's thought behind each character's name and their being.
One thing is that this does need a grammar check over. Multiple exclamation marks are good when texting and such to show extreme excitement, but when it comes to stories, it takes away from the value of them. It makes them feel somewhat childish.
Also, in "Outrunning the Demons", you say Geumji quite a lot. My suggestion is to change the first line to "Heart beating faster than a cheetah, legs aching from all her running, Geumji dashed..." etc. You only need to use a character's name once in a sentence so long as they are the only subject of the sentence.
It could also be helpful to describe the scenery a bit more, perhaps take a paragraph to describe the room before it's broken down, more than just the items inside. Describe the feel, is it old and rich? Dark toned? Dry and crisp? The room itself can give a lot of meaning to the events going on, it can help set the mood.
I also agree with Cylence that it is a bit rushed in the beginning. In just four paragraphs, Geumji is running, finds a house to shelter at, and meets a new character. You don't necessarily have to slow it down in terms of her literally running, but perhaps break each paragraph with flashbacks of why she's running. Not totally telling us why, but giving us a hint into why she's running away. Hearing echos of the scared voices of her parents as they realize she's a fire mage, or perhaps her imagining the breath of the Scarlet Huntress on the back of her neck. You don't need to slow the character's actions, just include other things, like thoughts and descriptions, to draw readers in so that they become one with Geumnji.
Hope this helps <3 It's a great start and a great idea so far! I'm actually very surprised there was little grammatical errors, usually most Wattpad stories are full of run on sentences and lack commas. Just little things I'm being picky about lol <3 Feel free to PM me if you have any questions, or want me to look over a specific part you're perhaps unsure about or need suggestions to advance!
~Bella