It's a very good story I really enjoy reading it

First off, I would like to say that I thoroughly enjoy your story. It's an interesting premise, and any suspense is pulled off pretty well. I would however, like to point out that your dialogue is rather... clunky. "I am" "you are" and other such phrases tend to make the conversations less natural. I would advise finding a way to make their speech more casual.

You'll need to watch your grammar. I noticed a few mistakes. But other then the chapters being short keep up the great work.

Here is the mistakes I found:
You are supposed to use "there" instead of their: "Mom, are their other creatures out there besides the Djinn?"

I think you meant "angels": There are the angles

I think you meant "your": they will do everything to make you not an issue

I just realized the title so this will be mostly about Mya. I wonder if you'll do a story about Rune then? Update soon!

This is an interesting story. I hope that the twins won't be separated for long. I have a twin brother and when we were younger we didn't like being separated so I understand Mya and Rune's feelings. But now that we are older we don't mind being separated as much. I hope that they will be able to find each other again. Keep up the great work!