The Balrog vs The Witch King

Originally Posted by obloquy

Besides, you're the one who asked what would happen if they fought.

The contest between these fell creatures is as much of wills than of might. My feeling is they would not fight each other physically, as I believe the battle here is a psychological one. It is also perfectly plausible that they could have met in Moria, in which case the Witch King would not be able to flee. For all we knew, the Witch King & his followers could have been hiding in the shadows of Moria until the Company arrived.