It is my understanding that Roman sexual mores were decided not only by position/active-passive roles, but further by class. For example, it was relatively normal and acceptable for an adult male citizen to have relationships of all kinds with other men, but they could cross the boundary into scandal by taking an unacceptable sexual role with a partner seen as equivalent in social stature (another adult male citizen) or, even worse, with a partner of inferior social stature, such as women, slaves, non-citizens, infamis, etc. Following this line of thinking, only an emperor could possibly be seen as having greater social stature than an adult male citizen of the senatorial class. This statement itself is up for debate, of course, given the sometimes nebulous nature of the Principate’s role in Roman society and government. But - could it be scandalous for someone of high rank to bottom for the emperor???

Although my question relates to all emperors of the Principate, I have an example: We know that both Trajan and Hadrian actively enjoyed sex with other men but here’s some selected passages on the nature of their tastes.

Cassius Dio, Roman History LXVIII, vii:4

“I know, of course, that he was devoted to boys and to wine, but if he had ever committed or endured any base or wicked deed as the result of this, he would have incurred censure; as it was, however, he drank all the wine he wanted, yet remained sober, and in his relation with boys he harmed no one.”

This could be interpreted a variety of ways, I think, but the main take-away I get from this is that it was with boys, not adult citizens, nor does it even specify that they were citizens at all. Dio was writing over 100 years later, anyway.

The other significant passage comes from the Historia Augusta (lol), so its authenticity is already doubtful and heavily anachronistic, but maybe somebody who understands historiography and philology better than I can glean something from it.

Historia Augusta, Life of Hadrian I, 2:7

“And now he became a favourite of Trajan's, and yet, owing to the activity of the guardians of certain boys whom Trajan loved ardently, he was not free from …[sic] which Gallus fostered.”

How can this be interpreted? Is this referring to favor as an heir? Favor as a sexual partner? Both?

Would Hadrian (roughly 22 years old at this time) be an scandalous partner for Trajan? I mean, setting aside the fact that they were cousins, Hadrian is an adult male citizen of at least equestrian stature. Would this defame Hadrian? Would this defame Trajan? Both? Neither? Would this, in fact, be treated or viewed as a significant opportunity for Hadrian to increase his social stature, by virtue of having a relationship with the emperor? Dio notes in the above passage that “…if he [Trajan] had ever committed or endured any base or wicked deed as the result of this, he would have incurred censure…”, but evidently states that he did not incur censure (specifically regarding boys in this instance, but Dio doesn’t mention any scandals about Trajan in general). Maybe this was considered scandalous, but Trajan’s favor towards the senate caused the writers of his time to politely overlook indiscretions like that?

Anyway, I would love some help from someone with a good understanding of Roman history and historiography in answering this question.