The Fellowship can't ride eagles to Mordor because of the giant, flying snake-dragon monsters ridden by
However, they were afraid of the men of the Vales of Anduin, who shot arrows at the Eagles (including the chief whom Gandalf saved) to keep them from stealing livestock. Therefore, the Eagles took the Company only a short distance.
They avoided the human settlers of Eregion because they knew they would be shot at with arrows (Gwaihir had himself been wounded by an arrow, later healed by Gandalf).
The eagles are not a taxi service. They will not fly into danger, they go to Mordor after the Ring is destroyed to rescue Sam and Frodo, because there was no longer any danger. The eagles are very intelligent, and do help Gandalf and others when they can.
When he came back as Gandalf the White he had forgotten many things, including the plan to meet the eagles. According to the Redditor, Gandalf's famous line, "Fly, you fools!" is actually him telling the Fellowship to go to the eagles. Then, of course, he forgets the plan and much of his past upon his return.
As for Sam, his resistance likely has to do with his innate goodness and loyalty. His love for Frodo helped him to overcome the pull of the Ring and his inner pureness was never fully pierced by the Ring.
Frodo asks Gandalf to take the Ring, but the wizard refuses vehemently. With the Ring, Gandalf says, he would become too powerful, and he would inevitably be corrupted like Sauron himself. Even if Gandalf took the Ring simply for safekeeping, the temptation to use it would be too great.
Radagast was unwittingly used by Saruman to lure Gandalf to his tower of Orthanc, where Gandalf was captured. Fortuitously, Radagast also helped rescue him by sending Gwaihir the eagle to Orthanc with news of the movements of Sauron's forces.
Yet, along the way little by little the ring is working its black magic on him, corrupting him as time goes. By the time he reaches the Cracks he has fully given in to the corrupting power of "power" and decides to keep the ring rather than throwing it in.
"The Eagles are a dangerous 'machine'. I have used them sparingly, and that is the absolute limit of their credibility or usefulness. "
Dwarves in Middle-earth have a reputation for being greedy, self-centered, and caring only for wealth. Because of that, many assume their absence from The Lord of the Rings means they refused to help defeat Sauron.
He wasn't truly omnipotent, but his great power allowed him knowledge of many things within the realm. Sauron insisted that the Orcs refer to him as the “Eye” because he did not allow his name to be written or spoken. So when the novels describe the “Eye,” it very well may be a description of Sauron himself.
After the death of King Elessar, Legolas made a ship in Ithilien, and through Anduin, he left Middle-earth to go over the sea. His strong friendship with Gimli prompted him to invite Gimli to go to the Undying Lands; making him the first and only Dwarf to do so.
History. The Great Eagles were the messengers and spies of Manwë, and possessed the ability to see through all physical matter, except for the blackness of Morgoth's evil pits. Morgoth first discovered the limits of their sight prior to the fall of the great stronghold of Utumno.
The reasons for the Elves inviting him are clear given his destruction of the One Ring and Sauron, but Frodo's reasons for accepting are less so. Ultimately, it was the injuries that the ring-bearer Frodo endured on his journey that pushed him to leave Middle-earth.
He's generally forbidden to use his powers to directly influence events in Middle Earth. He's supposed to be more of an advisor/cheerleader-type figure who helps the people of Middle Earth work to solve their own problems rather than them relying on divine intervention.
Gandalf's vision may not have been such so that he knew exactly what had transpired, and so he summoned three eagles to ensure any and all survivors might be rescued.
But Radagast was weaker and his role overshadowed by Gandalf's achievements. Therefore it is difficult to conclude whether or not Radagast failed. But it is clear that Tolkien had doubts following his criticism of him in the Istari essay and Radagast certainly did not fall into evil.
Together, the two of them were known as the Blue Wizards. The one in brown was Radagast and the one in grey was Gandalf, seemingly the oldest and the least of the Order.
It is unknown if Radagast left Middle-earth. J.R.R. Tolkien wrote that he forsook his mission as one of the Wizards by becoming too obsessed with animals and plants, so presumably failing, perhaps being disallowed to return to Valinor with honour.
It's a constant reminder to Aragorn of his family history; his hesitation to take the ring from Frodo Baggins (Elijah Wood) is a direct result of Isildur's corruption. Although Boromir ultimately falls victim to the seductive nature of the ring, Aragorn is able to defy his family history and resist his urges.
In the film adaptation, however, Gandalf mentions the Blue Wizards but claims he doesn't remember their names. This is actually due to a copyright issue because the names of the Blue Wizards don't appear in the trilogy. In hindsight, another good reason was that maybe adding Radagast into the story was enough.
Gandalf knew exactly where the Ring was, and who owned it. At any time he could've stepped in to help Bilbo destroy it if he did indeed confirm it was the One Ring. However, Gandalf would also have known how corrupting an influence the Ring can be. So he wouldn't have taken it himself, even if he had known earlier.
In the spiritual world, beings are invisible to those in the physical world. This is why Isildur, Bilbo, and Frodo become invisible when they wear the Ring—because they are no longer in the physical world. As Olsen said, Sauron does not have a real body, so he is not affected in the same way.
When Sam was wearing the ring, why didn't Sauron and the Nazgûl see this and come after him? Because, contrary to what Jackson depicts in his films, the Ring was not a homing beacon - outside of very specific circumstances.