Answer
In AD 4, Germanicus was adopted by Tiberius, the Roman emperor. Tiberius had no children of his own, and he wanted to ensure that Germanicus would succeed him as emperor. Germanicus was a popular and successful general, and he was well-respected by the Roman people. Tiberius believed that Germanicus would be a good leader, and he wanted to ensure that Germanicus would have the opportunity to rule Rome.