If Sauron was also a Maia servant of Morgoth, why is he not also a Balrog? The origin of the Balrogs dates back to the earliest days of Middle-Earth, before Elves and Men had even awoken in Arda ...

who is also a Maia and servant of Morgoth, didn’t become a Balrog when he pledged his loyalty to Morgoth? Before Morgoth fled Valinor, when he was still called Melkor, was the time of the Music ...