Voronwë_the_Faithful wrote: consider these words:
Therefore, though in the days of this darkness I seem to oppose the will of my brethren, the Lords of the West, that is my part among them, to which I was appointed ere the making of the World.
So, is Ulmo contravening Fate by sending Tuor, or is he actually Fated to contravene the Doom of Mandos? These words -- and the point you make about Huor's foresight -- would suggest the latter.
I think that from pretty much the moment he is first introduced in the Sil, "Ulmo's part" is to oppose the will of his brethren in matters pertaining to the Children of Ilúvatar. I don't believe that these words just apply to contravening the Doom of Mandos. Ulmo is set apart from the other Valar from the very beginning - it is inherent in his very nature, derived from Eru "before the making of the world:
"But Ulmo was alone, and he abode not in Valinor, nor ever came thither unless there were need for a great council."
<snip>
"Then again the Valar were gathered in council, and they were divided in debate. For some, and of those Ulmo was the chief, held that the Quendi should be left free to walk as they would in Middle-earth, and with their gifts of skill to order all the lands and heal their hurts. But the most part feared for the Quendi in the dangerous world..."
<snip>
Now Ossë followed after the host of Olwë, and when they were come to the Bay of Eldamar he called to them; and they knew his voice, and begged Ulmo to stay their voyage. And Ulmo granted their request, and at his bidding Ossë made fast the island and rooted it to the foundations of the sea. Ulmo did this the more readily, for he understood the hearts of the Teleri, and in the council of the Valar he had spoken against the summons...The Valar were little pleased to learn what he had done..."
<snip>
"And thus it was by the power of Ulmo that even under the darkness of Melkor life coursed still through many secrect lodes, and the Earth did not die; and to all who were lost in that darkness or wandered far from the light of the Valar the ear of Ulmo was ever open; nor has he ever forsaken Middle-earth, and whatsoever may since have befallen of ruin or of change he has not ceased to take thought for it, and will not until the end of days."
What a guy.
Mith, I think it was you who said in the Sil thread that you thought of Ulmo as a "counterpart" to Melkor. That comment really came to mind as I started mulling over a contribution to this discussion, and began rereading "Ulmo passages", some of which are quoted above. He
is a "lone rebel" of sorts, isn't he? But where Melkor becomes blind to everything beyond his own needs, Ulmo becomes ever more open to the needs of those beyond himself. Unlike Melkor, he doesn't reject the entire world in hatred and self-importance, he embraces it with love and compassion.
And unlike the rest of the Valar, he
chooses not to accept the Doom of Mandos.
What sets the "Doom" in these words that Mandos speaks? Is he speaking as the "mouthpiece" of Eru? Would Eru lay such a curse on his own Children? Would he cast them aside with no hope of redemption? I realize it seems to be the consensus on this matter, but it has never felt "right" to me that Eru would do this. So.....what sets the "Doom" in those words? And what gives it such power?
I think it's a matter of choice. Mandos lays out the stark and terrible consequences of the Noldor's actions, and they seem to stretch out into Time as a kind of "logical progression". In fact, I think it's probably more than just a matter of "seeming". This IS, undeniably, a path of Doom. The crimes, after all, seem unforgiveable, and the punishment fittingly unforgiving. But it is the Noldor themselves, and the Valar, and, I suppose, all the inhabitants of Aman, that choose to believe that the "Armour of Fate" has been forged strong and hard, that the Doom is set and irrevocable, that this path is the only path.
And in the choosing, the Doom is set and its binding power assured.
But Ulmo, the "loner", the great heart of the world, seeks for a "rift" in that Armour, for a "breach" in that Doom, by choosing not to believe in the absolute certainty of a path that cannot be changed. He sees beyond the terrible consequences falling like dominoes one upon the other until the utter end of the Noldor in Middle-earth, and knows, somehow, that there is still hope "unlooked for" that has escaped even the far-seeing gaze of Mandos and the wise heart of Manwë. He knows this, because he refuses to be bound by the limits of Doom itself. I believe he knows that
Eru's ultimate design for his Children must have some kind of light hidden and waiting even "where darkness was decreed", and he seeks it out and finds it so that it may show the way to another path, overlooked even by the greatest of the Valar.
Tolkien wrote:And thus it was that Arwen first beheld him again after their long parting; and as he came walking towards her under the trees of Caras Galadhon laden with flowers of gold, her choice was made and her doom appointed.
Tolkien also wrote:The last hope alone is left, the hope that they have not looked for and have not prepared. And that hope lieth in thee; for so I have chosen.'
Yes.....I do believe that for either good or ill, it is in the choosing that Doom is set.
And sometimes, "reset", thanks to a
"secret voice that gainsayeth". 
In the armour of Fate, there is ever a rift: there is always room for the will of God's creations to affect the destiny that He decreed. A light that shall pierce the darkness: 
Somehow it got marked as "read" and I didn't see it until this evening. I'm so happy that I did. Great stuff!