Offspring appears, recovering from outstretching after saving twenty members of Lex Luthor's 'Everyman' hero groups. Lex had deactivated their powers, causing dozens to fall from the sky. During his reappearance he is called "Ernie" by Plastic Man, not Luke. In Week 40, he assists Steel in launching an attack on Lexcorp when Natasha is captured by Luthor. He's later involved with the World War III, beaten by Black Adam, but able to recover fast, even joking with his father about the lack of humour of his superpowered foe, showing the same wisecracking and carefree attitude of his father.
In Countdown to Mystery it is revealed that Ernie is his middle name, and Luke his first name, ending the confusion.
Sometime after, Ernie was abducted by the Terror Titans for the Dark Side Club. Drugged and brainwashed, he was forced to fight against other teen metahumans in the Dark Side Club's tournament. He lost in the first round against the telekinetic Pristine. Ernie spent the rest of his time being brainwashed to serve in Clock King's Martyr Militia. During their rampage in Los Angeles, Miss Martian revealed herself amongst the teens as Star-Spangled Kid and snapped him out his drug-induced state. Ernie helped bring down the Terror Titans after this. Offspring is offered Teen Titans membership, but refuses.
Luke is introduced as Plastic Man's son, who grew up without his father but with the same powers. He is resentful to see his father after so long and orders him to leave him alone. After playing a game of basketball against his dad, he starts to warm up to him. When the rest of the Terrifics need help, Luke joins them as Offspring and aids in defeating a vampiric version of his father from another earth, all while accepting his dad in the process. Following this battle, he joins the team.
Luke has the same powers as his father, but Batman once said that he has even greater control over his powers then even his father does.
He has total molecular control of his body, giving him the ability to alter its size, shape, density, and even color so well that it is only limited to his imagination. He doesn't have an organic brain so his is impervious to telepathic abilities. His body is so durable that it can withstand acids, gunfire, temperature extremes, most types of energy attacks, punctures, and pretty much all other forms of harm. His extreme elasticity allows him to stretch any part of his body for almost limitless lengths.