"I CAN'T CHANGE," he cried, throwing the mighty hammer across the room for Sauron to dodge.
The Mighty's voice soon turned into a whimper."I- I've forgotten how! I can't change. I can't… Ever since my escape… Ever since I took the stones in my hands!" Melkor looked horrified, broken… and that alone would have been enough to frighten Sauron, even without the implication it held.
His Lord was plainly unwell. A figure imposing in size, of course, awe-inspiring to behold but beyond that… Sauron looked upon his Master's spirit. Trapped within its shell, it was diminished, shriveled, a shade of its once-majesty. Outshined a hundredfold by the hateful lights trapped in his iron crown.
Melkor turned to one of his many mirrors. He looked upon himself. Like his friend, he beheld his own spirit. Shining. Blinding. A Power above all Powers. Mighty Arising. Trapped, but undiminished.
"The wretched Hungerer. The abomination… SHE DID THIS TO ME! I WAS BLIND TO TRUST HER," he cried. The hammer flew back into his blackened hand, and with one swing he broke his reflection into a thousand pieces, silver shards like knives cutting across his skin.
He cursed. He ordered. He swore terrible vengeance against the Enemy which had defiled him so, his ivory skin growing blackened with each hateful word and promise.
Finally, he slumped, and his friend thought for a second he might be weeping.
"You are not less for it," he spoke to his Lord. "A thousand hungerers from the Void could not diminish your fire. Your form may be stilled but your power is still abundant." He came closer to Melkor, kneeling beside him. "The ages have changed all of us. Your brother no longer hears the Allfather's voice. Yavanna's Children are failing. The Champion himself is disallowed from leaving Aman for fear of the damage his strength would cause. All of the Ainur have changed-"
"You haven't." Melkor turned to him. "You are the same you have always been. You know no fear, you understand not failure, or regret." He reached with one hand to touch Sauron's face, beneath the gold of his hair. "A stone. You will outlive me."
"Impossible," replied the Maia without hesitation. "You will never die. I will, before I let that happen."