"Leave it to me Sauron."
These are the last words spoken by the white-robed Saruman in The Hobbit: The Battle of the Five Armies, by which time he and the rest of the crew have expelled Sauron from the Dark Forest's Dorgut Fort. Saruman's words were a promise that he would destroy the remnants of the Dark Lord's souls. But by the next time viewers see Saruman in The Lord of the Rings: Messenger of the Ring (which is actually his first appearance, the Hobbit series is a prequel), Saruman is already working for Sauron and imprisoning Gandalf. At this time, he was working to help Sauron destroy the Rokhanate, and also trained an army of orcs to wage war and help track down the Lord of the Rings. As the leader of Ishari (wizard), how did he fall to such an extent?
The film never gives an explanation for this, and Tolkien never pointed out the exact date or reason for Saruman's fall in the original work, but looking at Saruman's style, all fate was already doomed from the moment he stepped into Middle-earth.
Saruman's backstory
Saruman, like the five wizards of Middle-earth, is Maia, an angelic soul of the same level as Sauron, sent by Vera (similar to an archangel) to support the inhabitants of Middle-earth who resist evil in the third age. According to Tolkien's description, when they reach Middle-earth, they will lose a great deal of natural power, because Vera does not advocate the use of force directly against Sauron, nor is it allowed to use magical power to force others, and at the same time, they are at risk of fatigue, starvation, injury, and death like ordinary people. Because Vera gives them the same qualities as ordinary humans, giving them free will, they too can be tempted to deviate from their mission or even fall into darkness.
In Tolkien's collection of anthologies and story fragments, The Unfinished Story, the first Maia to accept a mission to Middle-earth is Kulumo, who is affiliated with Villaoli, the creator of the dwarves, and Sauron was his apprentice before the Fall. Coolomo volunteered to take responsibility, but attached some conditions to which he was reluctant to accept, including a requirement that he take Evendil (later Brownladhagast) with him. When another Maia, Olorin (later Gandalf the Grey-robed), accepted the appointment as the third wizard messenger, Coolomo decided that he would not be the third wizard to come to Middle-earth.
He was the first Ishari to reach Middle-earth, wearing a white robe, his jet-black hair and beard gradually turning white over the centuries, with elves calling him Kurunir and humans calling him Saruman. For more than a thousand years, he and two blue wizards have been active in the East (most likely Rune), but when Sauron's power in Dorgudu began to grow, he returned alone, and the whereabouts of the two blue robes are unknown. Saruman was very focused on his mission at the time, assisting in resisting Sauron's dark forces. In order to strengthen the protection and defense of humanity, he lived in Eisinger's Otank Tower and became the first line of defense against the forces of darkness, an arrangement that satisfied both the Rokhanate and Gondor. Kurunir, meaning "skilled man" in the elven sindarin language, became a master craftsman, becoming what Treebeard later called mastery of "metal and wheels." As the first to come to Middle-earth, Maia was the most powerful white-robed wizard and was chosen to head the White Council composed of wise men and elves who opposed Sauron.
The Fall of Saruman
However, even at this stage, while he was still serving the interests of the inhabitants of Middle-earth, Saruman began to fall into some vices. He was reluctant to take Evendir with him and had always held a contemptuous attitude towards Radagaste, even treating Radagast as a fool. At the same time, he also begins to be jealous of Gandalf, because Vera's extraordinary comments about O'Lourein have always haunted his mind and burned. There is also the Ring of Fire given to Gandalf by the elf Serdan, and Kelantril's support for Gandalf as the leader of the White Council, etc. This jealousy of Tolkien has been expressed in a rather comical way: "The Unfinished Story" tells how Saruman despises Gandalf's friendliness to hobbits and openly opposes Gandalf's smoking of pipes, but later secretly imitates Gandalf smoking pipes.
Saruman's jealousy led him to see Gandalf as a formidable rival, even as a man who was plotting against his plans. Later, when Saruman explores the process of making rings, he becomes jealous of Sauron again. Tolkien wrote in some sources that the greatest temptation Ishari faced was patience, and although they were instructed by Vera, their mission led them to impose a desire for good deeds in Middle-earth and hope that there would be enough strength to fulfill that desire. Especially after Sauron created the Supreme Ring, Saruman was eager to seek power from the Ring to fulfill his wishes, he found the final location of the Ring, and later even blocked the White Council's plan to expel Sauron from Dolgudur, hoping that Sauron would be free to find the Supreme Ring, and even help him find it, so that the Ring would soon appear and he would have the opportunity to take it as he had.
This key to evil occurred before The Hobbit, where Saruman never appeared in The Hobbit books, with only a vague reference to a council of "White Wizards" who gathered to expel the Necromancer (Sauron) from the Dark Forest. The Hobbit films fictionalized the timeline so that Saruman could be appointed head of parliament. In this prequel trilogy, Saruman is sometimes pompous and clearly shows contempt for Radagaste and opposition to intervention in the Dark Forest, but at the time has no other motive than overconfidence. In fact, many of the adjustments to Sauron's story in the "Hobbit" film series are not very meaningful and unsuccessful, but showing the audience the best side of Saruman is one of the few effective adjustments.
Saruman deceived the Middle-earth allies for the sake of the Lord of the Rings
After Sauron was expelled from the capital of Dorgu, Saruman claimed that the Supreme Ring had disappeared forever at the bottom of the sea in order to appease his Middle-earth allies, while on the other hand, he began to secretly search for the Ring himself. He began to covet valuable treasures in Osanketa and broke off his friendship with the Tree People. His fall was gradual, but his last line of defense collapsed when he arrogantly used Osankta's Crystal Ball of True Knowledge. The Crystal Ball of Truth is Gondor's seven "Stones of Insight" that can be used to communicate with each other across space and time. With his strong will, Saruman set his sights wherever he wanted, gaining a lot of useful knowledge. But when he turned the crystal ball towards Fort Baladur of Mordor, he was trapped by the Dark Lord.
The Lord of the Rings film does not depict Saruman's betrayal of Sauron
In The Lord of the Rings films, Saruman is completely subordinate to Sauron, and this relationship manifests itself as an almost complete obedience to servitude. In fact, in the original, Saruman was not so loyal to Sauron. When Gandalf approached him, he made Gandalf a condition that they jointly replace Sauron in ruling Middle-earth, and that his men and orcs send them to find the Lord of the Rings, in fact, to bring the Rings back to Eisinger, not Mordor. Saruman also created the ring himself and renamed himself "Multi-colored Saruman". When Gandalf discovers that Saruman is using the Crystal Ball of Truth, he realizes that Saruman has probably fallen to a more terrifying level than he thought. Gandalf's panicked escape forces Saruman to act, and if he wants to hide his true purpose and end up above Sauron, he must first take the lead, keep his secret, and take the lead in capturing the Supreme Ring.
All this came to naught, the Supreme Lord of the Ring was beyond his power, and his plans for the Rokhanate were thwarted. Saruman's final fate basically coincides in the book and in the movie, but the background is completely different. In the film, he tries to reveal Gandalf's whereabouts in exchange for his life, but his servant Grema kills him anyway. In the novel, Saruman is reduced to a vicious beggar who has lost his magical abilities, but despite this, he casts some kind of trick on the jailers to get them to release him, and then he rushes to the Shire and destroys the place in ruins before the hobbit heroes return, but is finally thwarted and dies at the hands of Grimma. As Maia's immortal soul, his "death" is not like a hobbit or a human, and if he stays true to his mission, he will return to the West where he came and be reborn, but because of his crime, he is deprived of this right. Tolkien wrote in The Unfinished Stories: "His soul withered no matter what, whether he was invisible or physically present, he was doomed to disappear into Middle-earth and never return."