So the common perception is that Narakasura was born of Bhu Devi and Varaha but it doesn’t say that in Vishnu Puran or in Bhagawat Puran.
Actually it does not even say that Varaha and Bhu Devi married! Which purana has that story?
Was Narakasur only the earths son? And if so if Varaha and the earth did not get married, then how does the Satyabhama tale fit in? Is Bhu Devi married to Vishnu or only Varaha? Considering that it was Krishna who killed Narakasura, ultimately, anyway.