Peter Jackson's adaptation of The Lord of the Rings remained largely faithful to J.R.R. Tolkien's seminal fantasy work. However, some characters -- like the superpowerful Tom Bombadil and the resurrected Elf Glorfindel -- didn't receive their due. Still, while most fans were pleased with the film trilogy, there was one scene in The Fellowship of the Rings where some didn't care for Jackson's interpretation: the interaction between Galadriel and Frodo in Lothlorien.
During their meeting, Galadriel considered accepting the One Ring when Frodo offered it to her. Then, suddenly, she was changed into a terrifying "dark form" that could easily conquer Middle-earth with the Ring's power. Understandably, the sequence may confuse some fans. Yet, Jackson's dark depiction of Galadriel --as "beautiful and terrible as the dawn!" -- makes sense, from a certain perspective, despite the moment straying slightly from the novel.
Galadriel's Darkness Was Portrayed Differently in the Book
For starters, let's note the difference between the movie and novel accounts. Tolkien's scene took place in The Fellowship of the Rings' chapter, "The Mirror of Galadriel." Jackson adapts that scene almost verbatim, but he took liberty with one word. Tolkien wrote that Galadriel "stood before Frodo seeming now tall beyond measurement, and beautiful beyond enduring, terrible and worshipful."
Note how Tolkien used the word "seeming." That may suggest Galadriel's dark form appeared only in Frodo's mind. It was as if the Ring had granted him a vision of what could happen if the great Elf were to wield its power. Jackson, on the other hand, used Galadriel's dark form as a visual cue for the audience. Specifically, it represented how she would become evil if she gave in to her deepest desire.
Galadriel Chose to Stay in Middle-earth After Morgoth's Defeat
Galadriel's story began well before the events of The Lord of the Rings. She was born in Valinor before the First Age, so she experienced the splendor of both the Valar and the light of the Two Trees. As a Noldorian Elf, she was inherently powerful, and as part of the royal lineage, she was a great leader. When the Noldor rebelled against the Valar, Galadriel was part of the rebellion and was exiled with the rest of her people, although she didn't take part in the Kinslaying at Alqualondë.
As part of the Curse of the Noldor, she waged war against Morgoth during the First Age. After the War of Wrath -- when the Valar cast down Morgoth -- most of the Noldor returned to Valinor. However, Galadriel chose to stay behind and explore Middle-earth. So, throughout the Second Age, she was one of the leading Elves, and as such, she became the recipient of Nenya, one of the three Elven Rings of Power. With her ring, she built and protected the realm of Lothlorien, which she maintained through the Third Age.
Galadriel Had Fantasies About Overthrowing Sauron
With her Elvish magic, years of hard-earned wisdom, and Nenya on her finger, Galadriel was easily the most powerful Elf in Middle-earth during Tolkien's trilogy. As such, she fantasized about what it would be like to find Sauron's Ring and use it to overthrow him. Her intentions would have been pure because she sought to instill peace. Ultimately, however, Galadriel would have been corrupted by the power of the One Ring, and her beauty would become an object of worship. Thus, Galadriel's dark form in Jackson's The Lord of the Rings personified what would have occurred had the Lady of Lothlorien given in to temptation and taken the One Ring for herself. She would have succumbed to evil because the Ring was indomitable, even with her power.
So, in the grand scheme of things, the two scenes were basically the same. The only difference was who perceived this vision of Galadriel. In Tolkien's novel, Frodo discerned Galadriel's dark form in his mind, while, in the movie, Galadriel represented her own temptations with a literal transfiguration. Some fans might have preferred to see Galadriel deliver her lines without being a dark figure, but all in all, it was a helpful, evil visual for the audience.