You fall in love with his eyes first.
Not just because they're beautiful — though they are, with irises so dark that you can barely see the pupils and deeper than the depths of the ocean — but because they're the only form of outward expression he has. His face is motionless, like a china doll's, and he controls his body and posture as carefully as he controls the Last Homely House.
But you look into his eyes, and you see care there, and weariness, and loneliness such as you yourself have never known.
OoO
You fall in love with his voice next.
In Council he is cold, clipped, but convincing. Inevitably it is his decisions that are agreed to make sense. And they do.
But when you lean against the door to the library, when he thinks that none can hear him, he reads poetry out loud. You would never have thought that he could sound so gentle, so caring.
You start reading out loud as well. Your taste in poetry is different, more dramatic and less soft, but you arrive at the same conclusion — these words were meant to fall from mouths, not to be mulled over on a page.
OoO
From there, you simply fall in love with him.
Love has always been all or nothing, with you, and you cannot love the look in his eyes and the intonation of his voice without also loving the curve of his lips, the inkstains on his hands, the movements in his shoulderblades, the slight wave of his hair.
You watch him and you love him, and you don't understand how anybody wouldn't.
OoO
He appears at your door one night, with tears in his eyes and shivers wracking his body.
"Please let me stay here," he says, in a voice that shakes.
You cannot refuse him. You do not try. Instead you let him in, lead him to your bed with a whisper-light touch on his back, and hold him close to your chest until he has cried out all his tears.
"I have nightmares too," you say quietly, lips pressed to his temple.
He nods like he knows already — and he probably does, when you first came to Imladris you used to scream in your sleep— and curls into you. "Can I stay the night?"
You can't believe it's even a question. "Of course."
OoO
When you wake the next morning, he's gone.
Neither of you speak of it again, but you're closer now. When he looks at you his eyes are warm, and he lets you touch him, sometimes. You smile at him, and occasionally he smiles back.
You fall in love with his smile too, of course.
OoO
It's only after Lindir points it out that you realise he loves you too.
The hints are all there: how he seems to take your side in Councils, how he speaks with you more readily and more warmly than with any other. Once Lindir says, "You didn't notice?" you can't understand how you didn't.
But you see it now, and every time Erestor speaks with you, you leave smiling like an idiot. You don't particularly care.
OoO
When you're both drunk on miruvor you kiss him, over and over until you're both out of breath.
"I love you," you say.
He frowns. "Glorfindel, you're drunk."
"Yes, I know," you say, "and I love you." You're smiling like an idiot again, you think, and it takes a few moments but Erestor laughs and kisses you back.
"I love you too," he says, with eyes that shine like supernovas, and you've never been happier in your life.