Two Kindreds was a collective name given to the two branches of the Children of Ilúvatar, the Firstborn Elves, and Men, the Aftercomers. The Elves remained bound to the World while it existed, so appearing immortal in the eyes of the other Kindred, mortal Men. In other respects the Two Kindreds were somewhat similar, and indeed they were combined on more than one occasion. Dior was the son of a Man and an Elf, Beren and Lúthien, and so had blood from both kindreds in his veins, and the same was true of Eldarion son of Aragorn II and Arwen as well as Eärendil the son of Tuor and Idril. It was Eärendil who succeeded in sailing into the West and pleading for mercy from the Valar, not for Elves or Men alone, but for the Two Kindreds together.