Gandalf was surprised. He seemed very surprised to find out that a Balrog had confronted him. How is this possible? Shouldn't he have known what terror dwelt in Moria? Let us examine the facts. Gandalf knows that the dwarves were driven out. He also states that they delved to greedily and deep and that they awoke "Durin's Bane". What does he think Durin's Bane could be? A troll? A great orc? A foul creature of the deep? Also, Legolas speaks of when the "dwarves awoke evil in the mountains", which frightened Nimrodel and caused her to leave. So, something sinister enough to drive away a group of elves shouldn't be taken into consideration? Celeborn apparently knew of "a terror". The survivors when the Balrog first awoke may have been too traumatized by the intense evil and massacre to relay the specific information (appearance, etc..) to others, preferring to die with their haunting memories, so it is possible that all the dwarves had to go on was an "evil" called Durin's Bane. Yet Gloin speaks of a "nameless fear". Sauron is the only other attributed with that sort of title. It seems to me that perhaps that when Gandalf passed through Moria the Balrog had receded a bit and he assumed the dwarfs were exaggerating. Then of course there is the matter of Dain. Dain says, "Only I have LOOKED through the shadow of the Gate. Beyond the shadow it waits for you still. Durin's Bane." The LOOKED implies that he saw something, whether it was a figure wrapped in shadow, or wreathed in flame. I tend to think it was the former, as a glow would have been too distinct and the White Council would have had to be retarded not to put two and two together (so many 2's in this sentence). Aragorn says the memory of Moria is "very evil". Come on, how evil could orcs be? He's battled them before but doesn't treat them with the same dark attitude as he does his Moria or Mordor experience. It seems to me that he has some prior knowledge of some terror residing there, Balrog or some other foul creature. So the question is, was Gandalf simply hoping Durin's Bane "wasn't as bad as it sounded"? And just hoping to stealthily slide through Moria despite the existence of this unknown Durin's Bane? Did he hope that Balin had enough of a resistance that the path would be relatively easy despite Durin's Bane? Was a Balrog never even considered into the equation of the Third Age? Perhaps no one knew any more existed, although some obviously escaped the Great Battle. But remember, just because WE know some escaped doesn't mean the Maiar or even the Valar knew. Doesn't anyone else wonder about this?