Powerless

Just follow the publication order, that is also the chronological order of events.

Start with Powerless.

Then read Powerful, that is chronologically at the same time as the 2nd part of Powerless, but follows Adena e Mak.

Next is Reckless, that follows Paedyn and Kai again.

Then read Fearless, that ends the story of Paedyn and Kai.

And finally Fearful, which follows Mara and Kitt.