Poisoned Kisses by Mandy Rosko

They warned her that the cobra’s kisses are poison…

John’s life has been one mistake after another. How does a normal human guy end up turned into a cobra shifter and then become a henchman for evil scientists? Just when he thinks he’s finally free, he ends up right back at the mercy of another.
Rachel and Matthew know they’re not supposed to exist. If FUC knew that their father used experimentation to save their lives, they’d be done for. But a new arrival has them curious about the world outside their bunker. Matthew believes the answers are at FUCN’A, while Rachel is captivated by the new prisoner. The things he tells her cannot possibly be true, but she can’t keep away from him either, and taking such risks could prove poisonous for her health.