What was Frodo's temptation

[Boromir88]

and what gave Frodo the mental fortitude to get the Ring all the way to Mt. Doom?~Inziladun

Simple, Frodo. If he had temptations to be the Dark Lord from before coming across the Ring (something I am not convinced of), then his ability to resist the Ring must come from Frodo too...correct?

"I think that this task is appointed for you, Frodo; and that if you do not find a way, no one will."~The Council of Elrond

Words of wisdom from Elrond that I share.

I do not think that Frodo’s was a moral failure. At the last moment the pressure of the Ring would reach its maximum - impossible, I should have said, for any one to resist, certainly after long possession, months of increasing torment, and when starved and exhausted. Frodo had done what he could and spent himself completely (as an instrument of Providence) and had produced a situation in which the object of his quest could be achieved. His humility (with which he began) and his sufferings were justly rewarded by the highest honour; and his exercise of patience and mercy towards Gollum gained him Mercy: his failure was redressed.

We are finite creatures with absolute limitations upon the powers of our soul-body structure in either action or endurance. Moral failure can only be asserted, I think, when a man's effort or endurance falls short of his limits, and the blame decreases as that limit is closer approached.~Letter 246

Sorry for a long quote, but I think we can learn a lot about Frodo and the Ring from this letter.

This is Tolkien's opinion, he also leaves the possibility that Frodo was a failure, as he "caved" to the Ring, he claims it as his own. For whatever reason, he fails and sees himself as a Dark Lord. However, Frodo had nothing left. His entire strength and endurance was spent.

It's not a matter Frodo having some desire to be a Dark Lord in his heart, while he was wasting space in Bag End. There is a difference between the Ring's power against individuals like Boromir and Gandalf, and the Ring's power against its bearer. Frodo took the Ring (where its essential power of deceipt was to fill people with the delusion of supreme power) to the place where it's power was at a maximum. In fact, I believe the only place where the Ring could get complete control over Frodo would be in the Sammath Naur. How many other characters in the books would you be able to say that about? That the only place to fall to the Ring would be in the Sammath Naur? That is certainly a lot different from Boromir having to make a moral choice while he's alone with Frodo near Amon Hen.

Boromir was corrupted, because right from the reader's first meeting of him, he views the Ring as a weapon that would save Gondor.

Gollum kills for the Ring, because he thought he deserved it.

Frodo doesn't "take" the Ring from anyone, it is left to him by Bilbo. And when he's instructed that the Ring has to be destroyed, Frodo says that's what he wishes...the Ring's destruction. That is a bigger sign of Frodo's character, than the tired, hungry, twisted, spent of strength and endurance, and delusional Frodo we see in the Sammath Naur, where the Ring's power was at it's greatest influence. Not to mention Frodo endured all that pain to get the Ring to the place where it could be destroyed. It wasn't Frodo finally caving into some hidden desire to be a Ring-lord, it was a matter of the Ring being greater than a physically and mentally beaten down Frodo.

As an aside, that is completely off topic, but if you want to blame someone, blame Gandalf. I'm in the opinion, dealing with conspiratory lore, that Gandalf is Sauron.