Assuming that Maglor and Maedhros fostered Elrond and Elros together, wouldn't raising the two boys have brought back painful memories of their early life and the younger brothers they had lost? (A double drabble.)
An Old Familiar Song
The chill autumn wind that lifted his hair reminded him that they should soon move on--a good bit farther south, perhaps closer to the sea again.
The skittering of dry leaves across the ground prompted the addition of a few new notes to the melody he unconsciously composed as he walked. His heart lightened at the warm, amber glow of candlelight visible through the window of the little shack. He jogged down the shallow incline, now hearing, in the low, resonant voice of his brother, the strains of a lullaby from his childhood.
Opening the door, he entered. Unexpected, unwanted tears wet his cheeks as he met his brother's vivid eyes.
"It was your singing."
"Was it truly that awful?" Maitimo asked, his tone dry with an undercurrent of feigned amusement.
"Do not be a fool," he said, bending over two nearly indistinguishable raven-tressed heads, childish faces slack and rosy in sleep. "It made me think of the others. You were the best older brother we could have ever dreamed of having."
The taller Elf crossed the room in two strides. He folded his brother in his arms and softly held him, humming the old, familiar song.
Inspired by reading too much Silmarillion (and Súlriel's and greywing's WIPs and, of course, Dawn Felagund's lovely novel Another Man's Cage).