Okay, first off a confession... I've seen this story as it's taken shape. So I know at least some of what's coming. But I've also been waiting very impatiently to rec it.
Endurance Without Hope is by Bill the Pony. It's Frodo/Sam, definitely NC-17 and angsty, so consider yourself warned if you don't like any of those kinds of stories.
It's also a Sam and Frodo are reunited in Valinor fic.
Do you know how very seldom I read
anything set in Valinor? I can count the fics I've liked on this subject on the fingers of one hand and still have fingers left over. (Well, okay, if you include drabbles I'd have to use both hands, but still...) At any rate, this one I like. A lot. Here is a Sam who has lived a long and happy life in the Shire, a hobbit who has come in hopes of regaining a possibility that had seemed lost to him, but has no regrets for enjoying all the possibilities he had in Middle Earth. And here is a Frodo who has healed in many ways, but has nearly lost as much as he gained in his choice to sail away.
Oh, don't just sit there staring at my entry... Go Read!