Offspring

The Kingdom
Offspring originally appeared in the out-of-continuity comic The Kingdom. Luke O'Brian is Plastic Man's son and had his father powers and sense of humor. He took the name "Offspring" and became a superhero.  Micheline, Luke's girlfriend, became frustrated with Plastic Man's spying and playing jokes on them. She also didn't like how no one took Luke seriously as a superhero (due to his humorous nature). She voiced some of her concerns to Plastic Man posing as Offspring. Offspring attempted to stop Brainiac, but his friends gave up since they didn't see the point since the end of the world was coming. Offspring met with his dad. Plastic Man apologized for being a terrible dad only for Offspring tell he wasn't. The duo chose to help Nightstar fight the destruction of reality. He was among the heroes that fought Gog at the climax.
DC Universe
Luke was introduced in the main DC universe. When Lex Luthor deactivated the powers of his "Everyman" heroes, Offspring saved several that were falling since they were flying before their powers were turned off. Oddly, he is called "Ernie" here (even though his name is still Luke). He later helped Steel fight Lex Corp (who kidnapped Steel's daughter Natasha) and fight Black Adam in World War III. During the latter, he displayed a humorous personality similar to his father. During Countdown to Mystery, Offspring's middle name was revealed to be "Ernie" hence the weird misnaming. Later, Ernie was kidnapped and brainwashed by the Terror Titans to fighting in a tournament for the Dark Side Club. When he lost, he worked for Martyr Militia until Miss Martian freed him. He helped the Teen Titans fight the Terror Titans, but refused to join the team.
Powers
He has powers similar to his father. He can alter his size, density and shape. He is also able to stretch his body endlessly. He is immune to telepathy. Unlike his father, he can change color, is immune to extreme temperature and acids.
References:
http://www.comicvine.com/offspring/4005-43304/
http://dc.wikia.com/wiki/Luke_O%27Brian_(Earth-22)