The politics of the imperial family had, however, produced other aspirants for the throne. Augustus had married off his second stepson, Drusus, to his niece, Antonia II (Antonia Minor, Antonia the Younger). At the time of Drusus’s death in 9 B.C. they had two sons — Claudius, the later emperor, and Germanicus — who were thus great-nephews of the emperor. Claudius received little notice initially because of a physical handicap, but for Germanicus a marriage was arranged with Agrippina the Elder, Augustus’s granddaughter from the marriage of Julia and Agrippa. Germanicus and Agrippina’s children included three sons: Nero (not the later emperor), another Drusus (III), and Caligula. At the time of Augustus’s death they were all still children, but unlike Tiberius they acquired the prestige of the imperial family by virtue of being the first emperor’s biological great-grandchildren and great-great-nephews. Augustus “solved” this problem by requiring Tiberius to adopt Germanicus, thereby opening the way to the succession for his great-grandchildren. The fate of Tiberius’s own son, Drusus II (Drusus the Younger) remained undecided. An attempt was made to resolve it by arranging further marriages between the different branches of the imperial family. Thus Drusus the Younger married Livilla, Augustus’s great-niece, while Livilla’s daughter in her turn married one of Germanicus’s sons, Nero. One last grandson of Augustus, named Agrippa Postumus, from the marriage of Julia and Agrippa, had fallen into disfavor for reasons that remain unclear. He was murdered in the year 14, possibly on Augustus’s own initiative or that of Livia or Tiberius.

These complicated family relationships — difficult not only for modern prosopographers, but probably also for contemporaries to keep straight — signal a central problem that resulted directly from Augustus’s construction of the Principate.