Mightiest of the Children by polutropos

Chapter 1

"And [the Valar] mourned not more for the death of the Trees than for the marring of Fëanor: of the works of Melkor one of the most evil. [...] And it was told by the Vanyar who held vigil with the Valar that when the messengers declared to Manwë the answers of Fëanor to his heralds, Manwë wept and bowed his head."
The Silmarillion, 'Of the Sun and Moon and the Hiding of Valinor'.

"Thereafter shall Earth be broken and re-made, and the Silmarils shall be recovered out of Air and Earth and Sea; for Eärendel shall descend and surrender that flame which he hath had in keeping. Then Fëanor shall take the Three Jewels and bear them to Yavanna Palúrien; and she will break them and with their fire rekindle the Two Trees, and a great light shall come forth. And the Mountains of Valinor shall be levelled, so that the Light shall go out over all the world."
The History of Middle-earth Vol. 5: The Lost Road, 'Quenta Silmarillion Conclusion', section 32

The stars fall, pummeling the foundations of Taniquetil like blazing hailstones. The mountain trembles. Varda, my partner through all the long ages of Earth, takes the stars back into herself. She is light, and song, and she is young again. The fires sear her bodily raiment; it collects like silver ash about the feet of our throne.

Light of Sun and Moon and stars drifts through the seas of heaven like so much dust.

Arda breaks. My fallen brother is defeated forever. But I can find no hope in the End. Somewhere amid this confusion, the Light that will illumine Arda Healed remains locked in three Jewels. Ilúvatar has placed the fate of the World in the hands of his mightiest Child, and Fëanor does not come.

‘Where is he, Father?’ I ask. ‘The Spirit of Fire, whose marring lies at my feet? Yea, Father, do you deny it? ‘Tis I who is King of Arda, ‘twas I who failed your greatest creation.’

The One does not answer. All the sorrow contained in the Oceans of the World crests and looms above me. I, the Elder King, am afraid.

But ere the last light fades forever, Fëanor comes. In the shape of a white flame, every hue of light contained within him, he comes before my throne. I am laid bare before the naked power of his spirit, until I am naught but wind, and his heat sucks in all the airs that are my lifebreath. His fire feeds upon me, growing, growing so great that he might draw the last of me into himself. I surrender. There is utter stillness, a balancing, in the joining of my soul with his.

He releases me. I am clothed again as a King of the Valar, and he in the form he once possessed in the Noontide of the World. Nay – more beautiful, for his expression is at peace. He wears a smile.

‘So be it,’ he says, his voice like music. ‘By this reconciliation may Arda be Healed.’

He turns from me, and as he descends the mountain the land stills beneath his feet. The looming Ocean recedes and settles back into the deep basins and veins of the remade world.

From the mound of Ezellohar a great light spills out over the earth, and I know that the Jewels have been broken at last.

But by the mark he has left upon me, I know that alone among the countless reborn spirits rejoicing in the new world, Fëanor grieves.