Secret,
How many bishops were there in the 2nd century? 10? 50? 100? 1000? We don't know, and how many ones suggests may say more about their bias than reality. But I'll admit I'd be comfortable accepting, even saying Christianity was small in numbers during this period, that between self declared heretical sect leaders and those appointed proto-orthodox and Marcionite bishops that the numbers likely ran into a the hundreds.
Just to throw out a number - making the scientific observation that any number is a finite number - lets say we can agree on a really small number of 250-300 throughout the Empire (60 churches, averaging 5 Bishops over 60 years; an admittedly low number). How many of them do we know anything about? Maybe two dozen, including some that appear to be nothing more than names Eusubius might have made up. At most we know the names of 10%, but more likely less than 5% - I would hazard to say less than 2%, as most were unremarkable. Note for comparison, how many Roman legion commanders and generals do we know? Not many. Now throw in significant priests who never were elevated to bishop and you quickly realize we know barely a small random sample.
Now this is where I have problem with your comment of imagination. It sounds to me more of a license for wild speculation.
Even if Peregrinus was based on a real preacher, a real sect leader (and there were many), is it likely we actually know who it really was? Probably not, the statistical probability is at least 10:1 and more likely 50:1 on a good day. That is why I am very cautious to assign a name to any such character. Now if the character is a composite, pulling together different characters, perhaps like Dialogue Adamantius taking on one then another heretic, only presenting them as one single character. So for the story we have a man switching religions like fashion model changes dresses.
What I am trying to say is, there is huge uncertainty here, and many different scenarios to account for Lucius' chameleon character, and that includes a number of purely fictional characters. The relationship to real characters could be like Alice in Wonderland, satire with targets hidden to all who don't know the slang. And we really don't know Lucius' slang. Perhaps he is taking swings at one then another popular figure and movement of the day.
There is a monomaniacal obsession (nod to Peter Kirby
) to find the exact person this applies to. Speculation like this makes me shiver, and I refuse to go there. The probability any of the speculations are correct is very small.