Answer
Marcus Aurelius and Lucius Verus succeeded Antoninus Pius as co-emperors. Antoninus Pius had no children, and the senate decided that Marcus Aurelius, who was Antoninus's adoptive son and heir, would rule together with Lucius Verus, another adopted son of Antoninus Pius. Marcus Aurelius was an intellectual and philosopher, while Lucius Verus was a more military man.