
Originally Posted by
Harper_of_Gondolin
No.
Boromir is frustrated at the waterside and throws a stone into the pool: shortly thereafter, there is a frothing action that moves to the shore, and tentacles emerge to molest the company. There is nothing at all to suggest that the Watcher attacked Frodo especially, rather then just first among all, aside from the nebulous idea, "the malice of the Ring attracts evil creatures", that is alluded-to in many places of the text.
As to speculations about "some kind of elaborate trap set at the West Gate of Moria, conceived by Saruman/Sauron" ...
The West Gate was shut (and hidden): this was common knowledge; Gandalf's purpose was to evade spies by attempting to use an "impossible" road (the only road that, he could hope, would not be watched); he hoped that Gimli's insights into works of similar Dwarf-craft, plus his own Wizardly perspicacity, would help him figure out the trick of how to open the doors from outside.
Clearly, the Watcher had been driven-out of the Deeps and into the pool by the orcs of Moria, as a watchdog posted at their "back door"; presumably, they had dammed the stream beforehand precisely for this purpose. There is nothing to say, however, that this had not been done at the bidding of the Balrog. Whomever conceived of the plan, they did it decades before the Quest to Mordor (a dwarf of Balin's party was taken by the Watcher), and they neglected to keep the stream properly dammed-up: when the Fellowship arrives, the water has receded some distance from the doors.
Back to topic,
Durin's Bane commanding the One Ring would be both more-, and less-, fearsome than Sauron, Saruman, Gandalf, Elrond, Galadriel, et al. The Balrog is a maia that has invested a great amount of the power of its fea (spirit) into its hroa (corporeal body): a demon of fire and fear, but locked into that terrible form (bound to its body in much the same way that Sauron bound himself to the Ruling Ring); with the One Ring, it would become an individual elemental force of terrible magnitude, but with little capacity for anything more (Sauron and Saruman coveted rulership of the entirety of Middle-Earth; Galadriel described herself transforming into a Queen that all would love, and despair ...).
HoG