So I wrote this little something inspired by the headcanons of @hadhafangtxt
Nothing could have prepared Elrond for what he heard. Hearing his brother, declairing that he would lead a life of a man instead of the elves. He always thought that they will be at each other's side for ages to come if fate allowed them to live that long but now that time was shortened by much. His ears were ringing. His parents, Maedhros, Maglor... all of them he had loved and lost and like it or not his brother's name would be on that list. His heart was beating furiously, his blood rushing, thumping in his ears.
But then he turned towards Elros. His brother was smiling, grey eyes twinkling, as he looked back at him and Elrond's heart calmed down. As he looked at Elros, a face as much or better yet even more familiar than his own a strange sense of calm overcame the feeling of lost. He knew Elros like the back of his hand. He knew that he would be a great King, that he would lead a long and happy life and how can a brother wish anything more than that for his sibling. And also, he was more certain in the fact that the two of them would always love each other, even when Elros have passed beyond the circles of this world. And different fates of elves and man be damned nothing, not even Eru himself could separate them forever and they will find each other again after the both of them died.
Elros's eyes lit up when he saw Elrond which made Elrond's lips twist upwards in a smile. "Muindor nín." he said gently as he hugged his brother. Elros was old. He was still strong, but his hair was now the colour of snow, he was sporting a mighty beard of similar colour, his skin was wrinkled and Elrond could feel the fragility of his bones as his arms wrapped around his brother's back.
"Brother." Elros said smiling brightly as tge they moved to sit in his chambers. "Still looking like a child, I see."
"At least I do not like I have one foot in the grave." Elrond said, yet immediately wanted to bite his tongue. The response was familar and easy, a routine they played every time Elrond came to visit his brother, yet now it felt heavy as for the reason of his visit.
Yet Elros laughed loud, and heartily and Elrond basked in the sound. He held his brother's hand. Elros's wrinkled and sun kissed skin against his own. Yet he could feel the familiar callouses, and saw the white line of scars that he himself treated once upon a time. Elros was changed and yet unchanged. The wrinkled skin, the white hair were all marks of the time passing that his brother wore well as he lived a life full and were the part of Elros just as much as the mischevious glint in his eyes or his hearty laugh.
The twins spoke for a long time, reminiscing back to their childhood, or talking about recent matters before Elros looked at Elrond. Words were not needed as Elros laid down and Elrond took a seat beside the head of the bed. "Do not weep for me brother." Elros said. "You know just as well as I do. This is not a goodbye. It is a farewell."
Elrond nodded suddenly finding speach hard. Yet when Elros reached out, Elrond's hand was already there grasping his brother's.
"Will you sing?" Elros asked.
That's how Elros Tar-Minyatur the first King of Númenor left the circles of Arda. With his brother at his side as Elrond sang and held his hand as it grow cold.