Aelius was adopted by an aging and ailing Hadrian in 136 and named successor to the throne, although he had no military experience; he had served as a senator. He had powerful political connections, but was in poor health. His tastes were luxurious and extravagant and his life said to have been frivolous. Hadrian's choice seems to have been an error in judgement. Some scholars have suggested that Aelius may have been Hadrian's bastard son, but there is no reason to believe this.
Aelius was the father of Lucius Verus (December 15, 130 - 169) who was later to be co-emperor from 161 until his death in 169.
Aelius himself was never to become emperor, dying shortly before Hadrian. After the death of Aelius, Hadrian adopted Titus Aurelius Fulvius Boionius Arrius Antoninus Pius (September 19, 86 - March 7, 161) on the condition that Antoninus Pius himself adopt the younger Lucius Verus and Hadrian's nephew by marriage, |Marcus Annius Verus (April 26, 121 - March 17, 180). Marcus later co-ruled with Lucius as Marcus Aurelius until Lucius death in 169, at which time he was sole ruler until his own death in 180.