The key words I'm using here is "project" and "inspired."
My first published book was a ten year labor of love. The inspiration came to me in a Sunday School class lesson. It was about the Apostle Peter visiting the Roman centurion Cornelius. The first gentile converted to Christianity, from the book of Acts.
I just read the first of Collen McCullough's book The First Man in Rome. I knew that this Cornelius of the Italian Cohort, was from the Cornelius clan. The Italian Cohort made it comprised of freemen from Rome and their leader from there too. He could possibly be related to Lucius Cornelius Sulla, a dictator during the civil wars. This Cornelius was on his way up the Cursus Honorum. The first gentile convert was the Roman equivalent of royalty.
You have no idea how detailed and inclusive all of McCullough's books on Rome are concerning the every day life and society, politics and economy of Rome. She made me want to write a book about Cornelius.
While researching the possibility I read F. F. Bruce's New Testament History. When discussing the early persecution of Christianity, he mentioned the first empire wide persecution was under Domitian. That he was childless and his aunt was charged with atheism tainted with Judaism. She was fined. Her two sons were Domitian's heirs. It would have been possible they were Christians and one of them could have been the first Christian emperor.
Out of the blue, or providence, I remembered a lecture in seminary in New Testament history. When discussing the Apostle Paul's incarceration in Rome, Christian tradition says that the authorities had to replace his guards because he kept saving them.
I created a Praetorian Guard who gets saved and is befriended by the son of Cornelius, also named Cornelius. He's also a Christian and when Optimus is saved they try to put a Christian on the Eagle throne of Rome.
It took me twelve years to finish the story. I knew the assassin who killed Domitian was a freedman named Stephanus. I made him the son of Optimus and how close it was that a Christian would mount the eagle throne.