At least come with me and listen to him! Mairon insisted of his brother in the Thought of Ilúvatar.
“No.” Olórin, who had taken the form of one of the Children that the Valar had drawn so closely to their presence, shook his head. “I have no interest in hearing the words of Melkor.”
But he is the Master of Light!
“He is intended to be the Lord of the peace of Darkness, my brother, not of Light itself. He encourages our kind to impatience and to cruelty, to destruction rather than nurturance. You would do better to return to your friendship with Lord Aulë.”
Pah! What does he know of Light?
“But he has ever taught you to use your affiance for Fire well!”
As does Melkor!
“And it pleases you to take the form of a Urushigasaz? To have your form burn whatever you touch to ash?”
You, too, could take this form. You, too, are more of Fire than any of the other elements.
“But I would prefer to be the Fire that warms and protects rather than the Fire that destroys!”
Losing his patience, Mairon departed, throwing over his fiery shoulder, The more fool you! as he went.
But he did not confine himself to only the form of one of the Burning Ones as did some of their order who followed Melkor openly. He could dissemble, after all, and feared to lose his great intelligence to the lust for simple destruction, as did some who were even then being reduced by holding such a shape for too long. Mostly he took a shape beautiful to the eyes of the Children, and he did return for a time to the service of the Lord of Forges and the Earth, seeking to learn more mastery of power. It was possible, after all, to focus power through such a construct as a Ring….
Fire could cleanse, and through his use of it he could capture the life force of those whose bloody bodies were consumed by it. At first he tried to capture enough of this strength to force open the Doors of Night and to restore his former Master. But, when he realized this plan was in vain, he still found he could harvest such strength for himself, and so make himself more powerful. Why return to Aman when he could take over his Master’s place as the all-powerful Lord of the Mortal Lands? But first he would complete his destruction of the land the fool Pharazôn so loved, as well as leading the Valar themselves to see to the destruction of Pharazôn and his horde, borne Westward in the vain hope of wresting immortal life from the Undying Lands. He laughed to know he had so gulled the seemingly all-wise King of Númenor. Not so powerful or wise had he proved as he fell to sudden age and was imprisoned beneath Aman with his Men, all of them insensible, until Time at last forsook Ëa. And he was laughing still when the waves broke over the dome of his temple and all sank in ruins into the Sea.
But his laugher stilled when he realized he’d held the beautiful shape of Annatar too long, and that with the destruction of the Star Isle he’d be unable to take that form ever again!
It was as a shade, as a shadow, that he fled back to Middle Earth in search of his hidden Ring. But even with It in hand he could not take again a proper corporeal form other than that of a mere werewolf or a vampire bat. It did not displease him that he was now revealed as Shadow, but galled him that in order to be seen by most of those he would rule he must surround himself by fire—until he realized that the appearance of being a great Eye struck them with even more terror and awe!
And so he was blinded by the false Light of apparent power.