Shadow Me by Tahereh Mafi

Juliette is still reeling from Warner's betrayal, and Kenji is trying to balance his friendship with her with his responsibilities as a leader of the resistance against the Reestablishment. Things get even more interesting when an unexpected person from Omega Point’s past surfaces. The ending of Restore Me left readers gasping, and this novella full of Kenji’s signature sass and big heart is the perfect story to tide fans over until Defy Me, the shocking fifth book in the Shatter Me series.