Four by Veronica Roth

This book, in the Divergent series, is told by Tobias Eaton, otherwise known as Four. This book has prequel elements, but it also takes place within the Divergent main series. Everything is told through just Four's perspective which was used in Allegiant, but this entire book is in Four's POV. The exclusive scenes were nice, but I felt a bit hurt reading the book (I can't tell you why because spoilers.) I recommend this as a read for a diehard Divergent fan. If you're not one, it wouldn't be my first choice.