The Balrogs may well be described as the 'fists of Morgoth'. They have played a major part in every one of the five battles of Beleriand, and also have hand their hand in the deaths of many an Elf, Feanor, Fingon, Ecthelion and Glorfindel the most renowned among these. Second among the throngs of Melko in strength/prowess only to the Dragons they are certainly a force to be reckoned with, and are thus included among the RRs of the MUX.

Admittedly there is not a lot known of the Balrogs for a certainty and so what is said bellow may not be in total agreement with various theories out there, but it will be considered true for Beleriand MUSH.

The Balrogs were once Maiar, though not only of Melko's, Morgoth seems to have corrupted more than his fair share of Maiar (The Silmarillion P. 26).

The literal translation of Valaraukar and of Balrog is 'Power Demon' ('vala' and 'rauko' from the appendix to The Silmarilion), and as far as we are able to tell their power has not significantly dimmed from the time when they were Maiar. Clearly they no longer have certain of their powers, such as changing their form, as Sauron is still able to do, we will class this as a permanent effect of their corruption. The only true measure of the power they wield is to say that they were on par with Gandalf, a Maia himself, though again slightly limited by the form he had chosen. Also they were a match for the best of the elves, dealing with whom was their primary role judging from the head count. A note about the killings of Elves, it seems evident that one on one a Balrog could not kill a Elf-lord and survive. In the cases of Feanor and Fingon, Feanor was not killed outright by the Balrogs, but only died of the wounds suffered by their hands and was saved by his sons who were able to beat back the Balrogs. And in Fingon's case in was only when restrained by another Balrog that Gothmog was able to slay him. Now all this gives them a wide range of powers, but for the purposes of the MUSH the following may be said: The Balrogs are primarily elemental beings, and specifically of fire, hence constant reference to fire-demons etc, though this is not entirely accurate. On Beleriand it will be allowed that they have an almost perfect control of this chosen element, and a lesser control over the others (earth, air and water). It would not be too far-fetched to say that they might consider these to be bellow them and not worthy of their attention.

The number of the Balrogs has also been a contested issue. Some say only a handful, others say many more. There are certainly hundreds of them though (The Book of Lost Tales, Part II, P. 171). This seems quite clear and final.

Another contentious issue is whether or not Balrogs can speak verbally, can they articulate words. The answer to this is certainly yes, though we have no reference to it from any first age source and must turn again to Gandalf's confrontations with the Balrog of Moria. Gandalf casts a door-shutting spell, which the Balrog is almost able to counteract, this implies magic of its own part. And since all magic in Middle-earth requires some sort of spoken word, the Balrog must then have been able to speak. Obviously in this case it was required to. For our purposes Balrogs rarely, if ever speak, choosing instead telepathic communication, projecting their words into another's mind. This is a far more controlling position one that we can assume a Balrog would prefer to use.

Reference:
As taken from J.R.R. Tolkien's The Silmarillion. Published by Ballantine Books ISBN 0-345-32581-8, Copyright 1977 by George Allen & Unwin (Publishers) Ltd.

P. 26
But he was not alone. For of the Maiar many were drawn to his splendor in the days of his greatness; and others he corrupted afterwards to his service with lies and treacherous gifts. Dreadful among these spirits were the Valaraukar, the scourges of fire that in Middle-earth were called Balrogs, demons of terror.

Reference:
As taken from The Book of Lost Tales, Part II ISBN 0-345-37522-X, Copyright 1984 by Frank Richard Williamson and Christopher Ruel Tolkien.

P. 171
Yet other creatures of pure flame that writhed like ropes of molten metal, and they brought to ruin whatever fabric they came nigh, and iron and stone melted before them and became as water, and upon them rode the Balrogs in hundreds.

The Balrogs take after their master in demeanor, sneering at all they consider to be lesser than themselves, which is pretty much everything. They have positions of authority in Angband as Captains and only defer to Gothmog, high captain, Sauron, Melkor's right hand, and Morgoth himself. Words that would describe them well: Egocentric, Control-freaks, Pompous etc.

A note on demeanor: Assume that the Balrogs bow to Sauron simply because Morgoth has told them to, otherwise they would just kill him off, Sauron hardly being able to handle hundreds of them.

Balrogs have the form of any Human/Elf, though perhaps slightly taller and bigger. This form, however, is not usually seen as they prefer to cloak themselves in shadows, which may, or may not, be a representation of the fear that they cast about themselves, however the shadows certainly seem to be visible enough. Balrogs can control the shape, and opacity of these shadows at will, and doing so may be a reflection of mood.

As to the 'Do Balrogs Have Wings/Can They Fly' question, the answer is a firm, unalterable no.

Balrogs were formerly Maiar corrupted by Melkor. Given the position of Captains of Angband they are a pompous group who control by fear. Formidable oponents they have slain many a renowned Elf. Cloaked in shadows they control their fiery nature.

Credits: Valkane