He goes unto the shoreline; he wonders and he waits. He thinks he espies Valinor, but this close to the gates of Angband light is found in forge-fire only. This wistful mirage is made by he who taught himself to hate the land; it's harder, hating light. Dark he dwells and dark he knows. Build the towers, break the foes.
He needn't have been faithful, but he chose to - he forsook the light. He's waited, waited patiently, for him, in all his might - he's made order out of chaos, it's his skill and it's his wont. Until he comes to Angband, its great halls he's bound to haunt - though some days, 'neath the scudding clouds, the shadows rising pitiless, he hears a tiny melody, a memory within. He dreams of light in dreams of darkness, and he makes himself forget, he makes himself forsake regret; he needs no bright lights now.
So when the wall of darkness flies - a cry rings out across the land, he feels the movement on the wind, a host of balrogs close behind -
He races down and beckons him back home, but on the hilltop, halts - he bows low once, his Master's servant, but it's mere formality. Something else has caught his fiery eyes, like sun and stars and moon. The balrogs pass behind him as he rushes forth in disbelief. Set within his palm, illuminating dark eyes, toothy grin, he sees a light beyond their making - feels a memory of Trees.
"What now have you done?" he breathes.
He steps forth, and presses a kiss to his Lieutenant's forehead. "I have changed the world for us."
This close, he can he feel the heat, the light, the power of the stones. He sees his hand is blackened, and he hates it - missing the light.