So much so, during the Second Age he even showed repentance for his actions as Morgoth's lieutenant. In The Silmarillion, Tolkien tells us about this brief period, in which Sauron was regretful of his servitude precisely for knowing the fate of Morgoth and wanting to avoid it for himself.
After the War of Wrath, with the downfall of Morgoth and the destruction of Thangorodrim, Sauron adopted a fair form and repented his evil deeds in fear of the wrath of the Valar.
Indeed he was. We know from some of Tolkien's essays on the subject that what Sauron liked about Morgoth, in the beginning, was his ability to get things done. Sauron liked everything orderly, with no contention from dissenting parties to delay and mess things up. Melkor/Morgoth didn't put up with dissent.
It seems that from the very beginning, Sauron only used Morgoth for his own ends, rather than being truly loyal to the latter. Their goals totally clashed with one another: Morgoth wanted to destroy everything, while Sauron wanted to rule - and if Morgoth succeeded, it wouldn't have been beneficial to Sauron's goals.
You have to think of it in terms of where we're meeting Sauron during his repentance stage. Tolkien says pretty explicitly in The Silmarillion that he is repentant — if not out of fear.
As it turns out, even after forging the One Ring, Sauron was still capable of feeling fear and regret. Actually, even during the War of the Ring and at the height of his power.
He was seeking a power, not to destroy Middle Earth, but to heal it”. The tragedy behind these words is that at this point, this is genuinely what he believes of himself, a savior and a hero, rather than a tyrant and destroyer.
Sauron desired to be a God-King, and was held to be this by his servants, by a triple treachery: 1. Because of his admiration of Strength, he had become a follower of Morgoth and fell with him down into the depths of evil, becoming his chief agent in Middle Earth.
All evil on Arda stems from him. But after Morgoth was defeated, Sauron ran and established himself as the Dark Lord. The First Age of Middle-earth ended.
The most powerful of the Valar other than Morgoth were Manwë (meaning “blessed one”), who became their king, and his wife, Varda (“sublime one”) who became queen. Manwë's area of dominion is the air and the winds, and the Great Eagles are his servants and messengers.
Sauron: Morgoth's Most Loyal Servant and Backup Plan
Morgoth's most powerful servant was his loyal lieutenant SauronOpens in new tab, a supreme being himself. Sauron was one of the Maiar, spirit servants of the Valar.
However, the mere fact that the Valar didn't prioritize perusing Sauron proved he was a much lesser threat than Morgoth. It made perfect sense because Morgoth was a Valar, and Sauron was only a Maia. So, while Sauron was evil, Morgoth was clearly much worse.
In The Lord of the Rings, it is said that had Galadriel chosen to use her powers for evil instead of good, she would have been even more destructive and terrifying than Sauron himself. Galadriel was the greatest and most powerful of all Elves in Middle Earth in the Third Age.
Sauron's identity was kept secret throughout most of the season, but it was revealed in the season finale that Sauron is actually the character we know as Halbrand (Charlie Vickers). He was adrift when Galadriel found him, and appeared to be genuine in his remorse (or at least regret) for his actions under Morgoth.
Lieutenant of Morgoth
The Valar made war on Melkor and captured him, but Sauron escaped. He hid in Middle-earth, repaired Angband, and began breeding Orcs.
At length, the Valar assaulted Melkor and took him in chains back to Valinor, but Sauron escaped, and remained in Middle-earth.
In Dagor Dagorath, the penultimate battle between good and evil in the legendarium, Turin is the one that will kill Morgoth.
In the War of Wrath, Morgoth was assailed by the forces of the Valar. Most of the Balrogs were destroyed in that War, but some few escaped over the Blue Mountains and hid in Middle-earth.
While Morgoth was defeated in the First Age, Sauron eventually returned and sought to conquer Middle-earth on his own in the Second Age. At one point, Sauron even managed to corrupt some of his enemies by convincing them to worship Morgoth, promising that his former master could save them from their own mortality.
Morgoth looms over The Lord of the Rings: The Rings of Power. Though the War of Wrath ended with Morgoth's defeatOpens in new tab, his touch spreads across all of Arda into the Second Age and beyond.
It was said that Morgoth hated and feared the House of Fingolfin the most of the three Houses of the sons of Finwe, and he feared most Fingolfin's son Turgon, as it was prophesised that from the House of Turgon would his doom come.
For The Rings of Power, Númenórian hatred of Elves built over time out of jealously for their immortality. In The Silmarillion, Tolkien outlines the downfall of Númenor as a slow burn that began with the Ban of the Valar, which entailed the first Númenórians agreeing to never sail west toward Valinor.
It is therefore unlikely that Galadriel would have been able to save him or turn him towards the light if she had agreed to rule beside him. She even tells him this herself when she whispers: “No penance could erase the evil you have done.”
Galadriel, however, didn't want to leave. She had already refused to leave once because she wanted to continue hunting Sauron. That's why she decided to lie about Sauron's identity -- so that she could go after him.
Galadriel Was Ashamed Sauron Tricked Her
There could have also been a darker reason that Galadriel didn't want to confess the deception. The events of the Lord of the Rings proved that Galadriel wasn't above temptation, further reinforced by The Rings of Power.