: The wods " it drew its self up to great height " do not mean that it changed its shape. If you are hunched or sittng slouched, and you straighten your self up, then you are drawing your self up "

snip

Actually, the text states, "The Balrog made no answer. The fire in it seemed to die, but the darkness grew. It stepped forward slowly on to the bridge, and suddenly it drew itself up to a great height, and its wings were spread from wall to wall; but still Gandalf could be seen, glimmering in the gloom; he seemed small, and altogether alone: grey and bent, like a wizened tree before the onset of a storm."

There is no indication before this that the Balrog was "hunched or sittng slouched" and indeed, it would seem that the term "great height" would indicate something out of the ordinary, rather then the coined term "full height". Further, why would the Balrog be "hunched of sitting slouched" after having chased the Company. Instead, as Mr. Martinez has suggested, the Balrog has some power to either change its shape or appear to change. In either case, I don't believe we are talking about the Balrog simply unbending his back. ;)

-RR