[Iarhen]

But why do you think that the Balrog would give up such a thing to Sauron? As far as I remember, even though Sauron was the greatest and must trusted servant of Morgoth, the Balrogs were not under his authority, only under Morgoth's. I dont remember where I read it, but not even Smaug (a lesser creature compared to the Balrog) was under Sauron's authority... Why would a being of equal nature such as the Balrog swear allieagance to Sauron?

Just imagine this: if Gandalf, a maia in a weakened form (because being incarnate and because the power ban that the Valar placed upon him) was the main danger for Sauron in terms of taking the One Ring and replacing him as a Dark Lord, why wouldnt a Balrog, a powerful ainu in all of his might, take the Ring and more easily supplant Sauron?

And, lets not forget that the One Ring had a lot of Sauron's original power in it... The Balrog plus that extra power, and the command of the Nazgul and all that was built under the One Ring's power... My guess is that Sauron would not last an instant against the Balrog with the One Ring on...