Sibling Mine - S2.E8

When Quark's Dr. Kirby disappears after an experiment with his Quantum Machine goes awry, a hostile monster emerges and goes on a rampage, apparently having destroyed the doctor. Back at Quark, Rusty discovers a previous ""boy robot"" prototype. Hoping for a new friend, Rusty reassembles the robot, who he names ""Earl."" But Earl's relentlessly aggressive programming turns him against the heroes.