Seabirds Winging West

Lúthien lives with Beren as an immortal until his time runs out. Someone's been waiting, of course, and is there to catch her when she starts falling apart. Or when she gets into fights with Orcs. (AU: Beren didn't die the first time, i.e. no trip to Mandos, and Lúthien is still immortal.) Lúthien/Thuringwethil.