[Boromir88]

We would think that, as observers looking 'in' on Middle Earth, but if we look at it through Boromir's eyes, it becomes a little different. He has been brought up as an heir to the Stewardship and would necessarily have the idea instilled within him that to protect and carry on the Stewardship was all important. He is in Rivendell on the orders of his father, and might find it very difficult to submit to the will of a king who is not-yet-a-king, in effect to supplant his loyalty to his father and to his 'office'.

Good point Lal, I think the oath Boromir broke was actually to Frodo. That is the oath he broke. Now he did not join the Fellowship to be a faithful companion like Sam. He merely went a long to head back to Minas Tirith, but whilst a member of that company, the oath was to protect the ringbearer, help him succeed. Well, when Boromir goes mad, that's when he breaks his oath, and nearly causes the failure of the quest. Then his redemption is recognizing what he had did wrong.

"I tried to take the Ring from Frodo," he said. "I am sorry. I have paid."

He realizes what he has done, and then asks for forgiveness. I don't feel as if Boromir broke any oath to Aragorn at all. Boromir had agreed to go to Minas Tirith, with Aragorn, and if he had lived and done so, then he could have broken an oath to Aragorn. Since, Tolkien wrote in another story, Boromir denying Aragorn's claim, and starting up turmoil. But, that's not what happened, and then Boromir's last words were.

"Farewell, Aragorn! Go to Minas Tirith and save my people! I have failed."

So from their first time meeting, in Rivendell, to his death Boromir doesn't do anything to hinder Aragorn's claim as king. But, he does hinder Frodo from trying to complete his quest.

Also, Lal, another thing between Aragorn's power, and Sauron's power. Is whatever power Aragorn has is his own right, it's his own right to claim the throne of Gondor. Unlike Sauron, he seeks to have power over everything, power that isn't his "right" to claim. Where, Aragorn doesn't seek to take power over anything that isn't his right. There's an interesting quote in "The King of the Golden Hall," where it appears Aragorn is trying to force his power as king (which he isn't yet) over the power of Theoden, but Gandalf stops him. Where Aragorn doesn't want to let go Anduril...

"It is not clear to me that the will of Theoden son of Thengel, even though he be lord of the Mark, should prevail over the will of Aragorn son of Arathorn, Elendil's heir of Gondor."
"This is the house of Theoden, not of Aragorn, even were he King of Gondor in the seat of Denethor," said Hama, stepping swiftly before the doors and barring the way. His sword was now in his hand and the point towards the strangers.
"This is idle talk," said Gandalf. "Needless is Theoden's demand, but it is useless to refuse. A king may have his way in his own hall, be it folly or wisdom."

This I point is is interesting because Aragorn, eventhough he isn't King yet, he tries to "override" Theoden's orders. Saying, I king of Gondor, should be able to over ride the Lord of the Mark, in his own house. So here Aragorn is trying to force his own power, over the power of another's. But as said, Gandalf stops him, and says a King shall have his way on his own "turf."