Specific characterizations are important!
When I read the first chapter, with the kidnapping,I almost forgot that this was a fantasy, not just a normal drama or thriller. When I reached the next chapter and met the Valor, I was like, "Oh, right." The shifting of the tone felt a little bit forced. It almost felt like a totally different story. Maybe you could make a better bridging by adding more details about Serenity's powers before she was finally at school.
Read the story now
The concept of supernatural beings in the same school isn't new, but I like the description of the school and how you built each creature.
I notice that you made it clear when you change the point of view by writing the name of the character, but except for what this character knew or did not know, I didn't feel any change in their characters (how they think, how they feel, how they talk, how they narrate their thoughts). They all sound the same to me. Even the boys and girls felt the same (the boys sound like girls, to be honest). There were no significant trademarks. This problem made me have a hard time loving the characters, because they all sounded the same with their past or family problems.
And how did all the boys suddenly fall in love with Serenity? I found it too annoying, because there are definitely other girls too, and they all loved each other. How come the boys never fell in love with Tora or Amber, but they suddenly liked Serenity? She didn't even do anything at first.
For the grammar, you got many typos and misspellings here and there. Also, you HAVE TO be consistent about the tenses you want to use. I noticed that you wanted to write the story in past tense, but the sentences keep changing into present tense in so many places, even in the same paragraph.
Also, when you write dialogues :
"It should be like this," I said.
"Instead of this." I said again.
Overall, your book might be interesting for middle school or high school girls, which is not a bad thing. If you strengthen several points I have mentioned here, this could be a potential.
Keep it up!