edit: deleted ^^ too late 😛 (why d'you type so slow today, exa?)
Beren took one > Thingol > Luthien > Dior > Elwing > Earendil ^^ ... in the sky
the others were taken by Maedhros and Maglor
one cast his into the Sea (Maglor?) and the other into a volcano
and in the End their light shall be united again
what is the direct cause for the Dagor Dagorath?