I cannot say how much I loved this. Caranthir and Haleth, whom I already shipped, were perfectly matched to one another. Their interactions and the slow slide into being husband-and-wife were believable and very cute. The difference in culture was just a detail that enriched the story enormously (especially when Fingolfin was scandalized at the very thought of half-Elven children ;).

I also like how, even despite it being a 'happy ending', not everyone survives. At first, of course, poor Maedhros, who only meant best, and second Celegorm and Curufin. I adore them (yes, I'm a huge Fëanorion apologist). I honestly thought at least Celegorm would not attempt to take the Silmarils, and I hoped Celebrimbor would calm his father enough for him to at least not jeopardize Maedhros' life.

I liked how things happen differently in your story but the results are more or less similar-ish: the Valar only listen to a half-elf, the army from the West comes to save the day, the Silmarils are retrieved, Maglor says his best words ("the less evil..."), Celegorm and Curufin do their bad thing and, of course, the Oath cannot be broken without dooming the oathbreaker. Poor Maedhros! He cannot seem to have a happy ending! Let's hope the twins' ship makes it to Valinor.