When I had said this, dearest Marcus Pompeius, I came to an end.
One thing I have noticed in Dialogue is the anachronistic way references to the bar Kochba revolt are made. Observe:
"Trypho, I am called; and I am a Hebrew of the circumcision, and having escaped from the war lately carried on there I am spending my days in Greece, and chiefly at Corinth."
... those with Trypho, having seated themselves on the one side, conversed with each other, some one of them having thrown in a remark about the war waged in Judæa.
There is certainly something amiss here. Justin's First Apology is typically dated to roughy 155-160 ad, with Dialogue making casual reference to it. Yet the discourse contained therein is written to have taken place ca. 135-145 ad. Indeed, in chapter 80, Justin tells of Trypho his intent of recording their debate in a book. Could this have taken him upwards to fifteen years to accomplish? The Dialogue is nearly three times the length of his First Apology, so the time needed to compose must be taken into account.
But then, as has been noted by others, the narrative appears at times contrived, and even fictional. Indeed, had this talk occurred during or close to the tumultuous upheaval of bar Kochba, Trypho must have been a very patient man. Many times Justin devolves into, what can only be considered, antisemitic attacks and blasphemous doctrines, going so far as to call Christians the true Israelites; and Trypho gets visibly upset, and at one point goes to take leave of Justin. But he stays to the end. This characteristic has led some to speculate that Trypho is merely a literary device.
But where does that leave the identity of Marcus Pompeius? Surely he would have to have had some importance for Justin to write down this discussion for him, and would have to be active, either during the forties or fifties.
I have one possible suspect, but that is only taking for granted that Justin's works are compilations of various other sources from different times, something that I can't say for absolute certainty as of now. Thoughts, anyone?