[Boromir88]

Interestingly, like the Watcher, the Orc chieftain makes straight for Frodo. Presumably, he is drawn to the Ring in the same way that the Orcs were drawn to Isildur in the tale of The Disaster of the Gladden Fields in Unfinished Tales.

SpM, interesting, so would you say that is an effect of the ring? That forces of evil are drawn to it? To ultimately kill the ringbearer, quite possibly losing the ring? Or getting it into the wrong hands?

Encaitare I'm glad you brought up that point about Legolas, I'm going to expand upon it just a tad.

"Ai, ai!" wailed Legolas. "A Balrog, A Balrog is come!"

Gimli stared with wide eyes. "Durin's bane!" he cried, and letting his axe fall he covered his face.

"A Balrog," muttered Gandalf. "Now I understand." He faltered and leaned heavily on his staff. "What an evil fortune! And I am already weary.

First I'd like to say with the quote on Gandalf, we can already see some sort of foreboding evil to come to Gandalf. In the previous chapter he stayed up all night on watch, and now Tolkien describes Gandalf as "faltering" tired as he "leans on his staff," and even admitting he's weary.

Then we have the quotes about Aragorn and Boromir.

The dark figure streaming with fire raced towards them. The orcs yelled and poured over the stone gangways. Then Boromir raised his horn and blew. Loud the challenge rang and bellowed, like the shourt of many throats under the cavernous roof. For a moment the orcs quailed and the fiery shadow halted. Then the echoes died as suddenly as a flame blown out by a dark wind, and the enemy advanced again.

Very interesting wording used here by Tolkien. First we get to see the might and power behind Boromir's horn. As it makes the orcs quail and even halts the Balrog in his tracks. Also, the interesting wording of the when the horn blew he used the word "challenge." While the horn "echoed" and "bellowed" throughout the orcs and the Balrog in a way were losing the "challenge." Then the next line "The echoes died as suddenly as a flame blown out by a dark wind," very nice, the challenge of the horn didn't last long, and as soon as it was out, they advanced. Mithalwen, I might post this on your Music and Magic thread, could hold an interesting point, about the "challenge" of Boromir's horn. As here we get to see the true power behind the horn, and then later again at Amon Hen.
Moving on...

Aragorn and Boromir did not heed the command, but still held their ground, side by side, behind Gandalf at the far end of the bridge.

Also, Encaitare, as you said, we have the two men of the company standing to help fight the Balrog. Of course we know it's a valiant proposal, but also utterly stupid. However, the question I ask, we have the Elf and Dwarf quivering in terror, the two men standing tall, is this a symbolism of the strength of men, and the fading of elves and dwarves?