Unfortunately without the Persian's account, the story lacks the deeper mystery. We miss out on the reason this foreigner took such a liking to a creature scorned, used and mocked. Why did he care?
Apparently Erik killed at the drop of a hat and got away with it in Persia, India or any of the Middle Eastern countries he'd traveled and lived in. Daroga or the Persian knew this and sought to stop him. His fear for Christine must have come from Erik's past behavior. Not just killing, but how did he react around women? Especially one he fancied? Had Erik loved before? Did it end in tragedy? Ponder a moment the real reason Erik released Christine and Raoul? I don't feel he did it because he was a gentleman and a scholar. Something similar must have occurred in the Middle East which ended badly; very badly. As insane as he acted, Erik did not wish to repeat a horrible ending, so he let the young diva and Vicomte go.
The character of the Persian actually tells a lot about Erik. Sadly, little is known about the man, except that Leroux claimed to have found him living in a small apartment not far from the Opera House. Five months later, he died after telling Leroux what he knew about Erik, his passion for Christine and what we know today as the story of The Phantom of the Opera.