Was Sauron a Balrog?

[alatar]

Originally Posted by Legate of Amon Lanc

Aulë did not seem to have any fire spirits.

Maybe he had one or two dancing around within his forge - no need to cut trees then.

But if fire-spirit is a fire-spirit... anyway, it looks that we can't tell even what Arien was... if she was Vána's, well, then what was there about the fire? The flame of youth?

Melkor and Manwe were brothers but went separate ways. Why can't fire spirits do the same? And what does any of that have to do with Sauron, who was never a fire spirit? Is Peter Jackson's volcanic eye depiction creeping in?