Existence (Existence Trilogy, #1) by Abbi Glines
Gregor and the Marks of Secret (Underland Chronicles, #4) by Suzanne Collins
Gregor and the Curse of the Warmbloods by Suzanne Collins
Gregor and the Prophecy of Bane (Underland Chronicles, #2) by Suzanne Collins
Gregor the Overlander (Underland Chronicles #1) by Suzanne Collins
Gregor and the Code of Claw (Underland Chronicles, #5) by Suzanne Collins