I disclaim all works of Tolkien. Oh, if only...
This story has an alternate ending, so please don't get confused. The first part is from Thranduil's POV, then the alternate ending is from Elrond's POV, starting from when the ship has docked.

I will tarry in Arda but for a little while, he told me.
I would see the days of Elessar fulfilled, and his legend laid to rest.

That is what he told me, as I lingered on the shores of Arda. The last scion of my house embraced me, and stepped back. I scarcely knew what to say. What words does one leave with their son when faced with a division such as this?

I love you, Legolas.
He smiled at me, and blinked away his tears, and I knew it was enough.
I love you too, Ada.

Spring blooms in Valinor, beautiful, vibrant and teeming with life. Summer follows with its golden haze, and in Autumn the leaves turn shades of red and gold, but do not fall. The absence of Winter is a dull reminder of the land I have left behind, and the son left behind in it.

I share my loneliness with Elrond, for all three of his children have chosen to remain in Arda, for a time. His sons will make their way here, along with my son. But the Evenstar… She is not coming back. He lifts his eyes to meet mine. Her choice has been made. The grief in his face speaks more than words could ever tell. I lay a hand on his shoulder, and we sit in silence for a while.

His wife is here with him, and for that blessing granted to him, I thank Iluvatar, for I do not know how I would endure being sundered from my little leaf forever, alone, with none who fully understood my grief.

Seasons pass, and the waves break upon the beach unendingly. We gather on the green hills overlooking the shoreline, at the start of every summer, welcoming the great Eagle of Manwë. He bears letters and other missives to us here in Valinor, making the long flight once a year. Our feathered envoy is well rewarded, for he is the only solid link to our missing loved ones. Today, there is another letter for me to add to my hoard.

The wrapped messages are passed along to those whom they are addressed to. A beautiful depiction of Estel and Arwen's little family is clutched tightly to Elrond's heart, and Celebrían smiles bittersweet at the likeness of the daughter she will never see again.
Their children look healthy, and strong, and I can see a great resemblance to the young troublemakers their parents once were. My son is there too, raising an eyebrow at the artist. It is an apt portrayal, I find myself murmuring. Then I open his letter.

There are only seven words. I'm coming, Ada. With love, your son.

At first I'm speechless. Surely there is more? Galadriel glances at me curiously, and I hand her the small piece of parchment. She glances over it, and looks at my bemused countenance. Her voice is tinged with amusement.
Need he say anything more?
Finally I smile.
No.

I await his coming with such impatience, my behaviour must be somewhat undignified. I remember when he was but an elf-child, running to greet me after a long absence. I remember his little legs beating a joyful tattoo on the ground, and his delighted grin welcoming me home. My elfling missed me, and I cherished his endearing greetings. Oh, my beloved Greenleaf…

And now, our positions are reversed, and I anticipate your coming the way a starving man would long for a feast. Oh, my son! Your ship cannot ride the waves here swiftly enough!

We stand on the crest of the hills, Elrond, Celebrían, Galadriel, and countless others I will not endeavour to name. Motionless we stand there, shading our eyes with our hands, craning our necks to catch just a glimpse of silver sails. I do not know how long we have stood there, and I do not care. All I want is to have my son back again.

The sun is setting behind us, lighting the city's marble on fire and lending a flickering quality to the light. Finally! The rays of the sunset pick out the silver sails of my son's ship! They are home! A loud cheer is raised from the elves around me, and I find my voice lifted in chorus. We rush down to the shore, surrounding the port and chattering in jubilation. I do not even know what I am saying, so ecstatic am I!

The gangplank falls to the boards of the pier with a gentle thud, and I swear, the dignified Elf-lords around me are almost jumping up and down. The first few elves walk off, and are greeted raucously by their kin and loved ones. I watch their reunion, feeling my heart swell up within me. Oh, little leaf, where are you?

And as though he has heard my plaintative plea, he is here. I drink in the sight of him. My wonderful, loyal son…He is here. I wrap my arms around him and feel him laughing from pure elation. I always keep my promises, Ada.

Galadriel is talking with…A dwarf?! Legolas smiles at me reassuringly. I named him Elf-friend, Ada. Gimli, for that is what he is called, brings a message from Celeborn, to the Lady of Light. He is coming. Do not fear. You will see him again, and from this next meeting, you will not be parted. He bade me tell you…

I turn away, for I am not privy to their conversation. Elrond and Celebrían are in a happy huddle with Elladan and Elrohir, and they are greedily taking in all the letters and drawings they have brought back. A few tears fight their way out, for the absence of the Evenstar is sorely missed, but she has found happiness, and who could deny Arwen Undómiel her love?

But as I turn back to my son, I know all the long years of waiting were not in vain. Legolas is back with me, and I am happy.

fin

Alternate ending as told by Elrond:

Thranduil is at the forefront of the crowd, impatiently jostling aside any who dare try take his place. It is almost amusing, except that my wife and I are the ones being jostled. We retreat backwards, but only a little. Where are my sons? I long to halt everyone in their tracks, and simply go running on board, hunting for my elflings.
Glorfindel strides down first, and I greet him in delight. We babble about the most inane things for a little while, and then he sees his father.

I push him towards the ancient elf, and smile at his childlike expression. Thranduil watches them as well, with a slight hint of jealousy on his face. But then he too, is claimed by his son. Celebrían pulls me forward, and we look around in all directions. Elladan stands before, and time stands still. He laughs, and tries to talk from within our loving squeeze, but…Where is Elrohir?

We step apart. I already know, but…No. No, it cannot be! No! Not my little elf knight…Elladan holds my hand, and Celebrían's too… He, who must be suffering the most, gives us strength.

I'm sorry, Ada. I tried.
Oh, I know, my son…I know how hard you tried...Please, don't be sorry, my brave one...
He…He said that his lot…was the lot of men. That he must share their fate.

I cannot speak anymore. I don't want to think anymore...

No...My Elrohir has made the choice of Elros...I hold my oldest son tightly, as I feel the heartrending sobs emanate from deep inside him. I know how you feel, ion-nin. But I do not speak the useless platitudes. They will be of no use. I know.

To have your twin taken from you is having half your mind and soul ripped away. Two sides of a coin should be never separated. But they can, as I know all too well…Long ago, my twin made the same choice Elrohir has.

I know Elladan will be strong. The pain will fade, for we are in Valinor, but always, always there will be a scar. And it will never heal. The three of us stand there, holding each other, yet somehow Elladan still seems alone. I do not know how much time has passed, but Elladan begins to breathe deeply, emerging from our protective cocoon. Oh, my little elfling...

He stands tall and straight once again, and our friends and people gather around us. Thranduil locks eyes with me.

We are here for you.

What can I say? I nod in assent.

I know.

Thanks for reading. Please share your thoughts, or ideas for another story =)