Who were the Nazgul?

Originally Posted by Legate of Amon Lanc

I think that the idea of "if the Nazgul ever encountered the balrog" would be most probably unimaginable in Middle-Earth. After all, Nazgul never encountered the Balrog and I think Tolkien didn't even want them to. He avoided things like this. We do not know enough about the Nazgul nor about the Balrog (do they have wings?) to decide such a thing, and the Professor didn't provide any such informations. As far as I now, that is.

The Nazgul could have acquired the services of the Balrog in Mordor. The Balrog then would have taken command as the chief servant of Sauron perhaps, although there is no evidence that the Balrog recognised Sauron as his master, only the now departed Morgoth.

Certainly Sauron knew of the existence of the Balrog (especially at the point when his orcs entered Moria), and the Balrog seems to have tolerated the presence of Sauron's orcs. Yet I do not believe that Sauron could have controlled or commanded the Balrog - at this time he lacked the One Ring which held a large part of his native power. Without the One Ring, Sauron would not have had the ability to dominate a will as strong as a Balrog.