Escape by Emmy Chandler

Sentenced to death for war crimes they didn’t commit, Captain Carson Sotelo and his team were given a choice: die in disgrace, or live as something entirely new. Several dozen procedures and a medically induced coma later, they awoke on a prison planet as super-soldier prototypes, spliced with genes from an extinct alien species.
Sotelo’s altered body comes with strange abilities and built-in weapons, and when Universal Authority tests him in the field, combat awakens violent instincts and cryptic genetic memories from the beast they installed in his genetic code. He’s able to keep the beast on a leash—until the day he meets Lilliana Malone, and his inner alien decides she’s his mate.
Though Sotelo resists the beast’s barbaric courtship style, he can’t pretend he doesn’t want Lilli. Her protective nature and fiery spirit remind him of why he went to war in the first place. Unfortunately, catching Sotelo’s eye also brings her to the attention of the ruthless team of scientists who turned his entire team into monsters…
Universal Authority had no idea what they were unleashing when they turned Sotelo into a weapon, and now that he has someone to fight for, he will bite off the hand that feeds them all, if that’s what it takes to get the team he leads and the woman he loves off the planet.