Addressing the Emperor

[Quintius Clavus]

I'm not sure that forms of address at the time of Marcus Aurelius would apply to the later period represented by AD 335. This is post-Constantine and the emperors were, to my understanding, more self-consciously "Imperial". Society was more rigidly heirarchical at this period, too. Ammianus' history might be a place to start since he is roughly contemporary. My copy is at home, unfortunately, so I can't go poking through it for gleanings of how the emperor was addressed (in either spoken or written communication). The imperial household structure was very formal, with more layers of bureacracy to get through before being able to approach the emperor, including Imperial eunuchs, something that Marcus Aurelius would have been horrified by. In any case, you want to look at sources from the Late Roman Empire.