You should make sure you read the description.
It’s in the Note From The Author section on Amazon and reads like this:
After completing Book 1, I knew it was time to introduce Zillael, who in my head had this entire backstory. She is falling for two supernatural creatures and how their association came to be is the focus of The Seventh Sister (Parched, book 2). However, and this is very important, the end of this book picks up right where it leaves off in Quenched (Parched, book 3) at the point where I’m ready to introduce Zillael into the main plot.
Also, this is NOT a YA novel series. This particular story is told by a high school student so her voice is young and so is her world. This is the ONLY book in the series that’s told by a teenager, however, we do see and hear Zillael in the rest of the series but circumstances are making her grow up fast, and right before our eyes.
If this is the first book you’ve read in the Parched novel series and you wish to continue reading on, then Parched (book 1) will be the next read. You shouldn’t move on to Quenched (Parched, book 3) without first reading book 1.