HAVING A CONVERSATION WITH MICHAEL Oliver, the star of Problem Child 2, is different from talking to most 9-year-olds. And not because he's as irredeemably demonic as his character, Junior, a creature the New York Times labeled "the worst role model a child could have." Michael's lively demeanor is more like that of Opie than Dennis the Menace. It's just that his interests are, well, a tad advanced. "He has a big problem getting someone to listen to him," explains his half sister, LuAnne, 20. "He likes to talk about jet propulsion."

Oh-oh. You can imagine Michael flashing that pet-torturing, nun-tormenting smirk (the one that made last year's Problem Child a $65 million hit) as he ignites a rocket under the chair of an unlucky guest. But a visitor to his hillside home south of L.A. can rest easy. Michael maintains that his predilection is purely academic. "I really understand a lot about space science," he says. "I read about it all the time."

Taking a break from his studies to play Junior again, Michael had to go head-to-head this time with (eek!) a girl. But, already a pro at Hollywood ego stroking, he says of costar Ivyann {Parenthood) Schwan, 7, "She was my favorite person in the whole picture. Although I did like John Ritter and the other people too."

If stardom is proving no problem for this child (his fee jumped from $12,500 in the original to six figures in the sequel), chalk it up to family influence. His mother, Diane Ponce-Oliveras, a former nurse, has shepherded two children from her marriage to supermarket clerk Luis Ponce through the business. LuAnne was featured in the Broadway hit Into the Woods, and Danny, 18, played Willie in The Hogan Family. After separating from Ponce in 1980, Diane moved in with auto mechanic-Matt Oliveras and began taking Michael, the eldest of their four kids, around on casting calls for LuAnne and Danny (both Diane and Matt now manage their kids' careers full-time).

Michael crawled into his first job—as a catalog model—at age 10 months. He was spotted for Problem Child in a 1989 Chevron commercial. "We auditioned a thousand kids," remembers producer Bob Simonds. "Then we sat Michael down and started to talk, and we said, 'Oh, God. Please be able to act.' " In fact, Simonds got not only an actor but also a miniature director. "One time they almost shot a scene with the microphone disconnected," Michael says of the original. "And I told them."

Despite his precocity, Michael, says his mother, is not a stellar student at his private school. She suspects he is "very, very undermotivated." But he is very, very ambitious, dreaming of a future as a spacecraft designer. "I don't always want to be an actor," he says. "By the time I'm a teenager, I want to get ready for a real job."