Let's say that the assassination of Emperor Aurelian in 275 is butterflied away for whatever reason—perhaps he learns of the plot ahead of time, or perhaps his secretary Eros never gets himself into trouble to begin with. Aurelian then manages to live another ten to fifteen years, founding a dynasty. In this scenario, who is he most likely to adopt as heir? Or alternatively, who would make the best (or most interesting) choice?
I assume the man would be unrelated by blood, as Aurelian and his wife only seem to have had a daughter and I don't remember reading of any nephews or kinsmen.