Here's an addition to the halfling and goblin setting text about their mythical origins. Note that this might not be altogether in line with what actually happened. My ambition has been to further anchor these kin in the setting and to give them a long-time quest that we might expand upon later. This take has been cleared by FL, but please give feedback!
The mythical origins of halflings and goblins
As elves fell to earth from The Red Wanderer of the sky, the moon goddess Eor got jealous and threw blue moonstones after them. From these grew dark elflike beings that were of little use and couldn’t abide the sunlight of their new world, so they claimed the dark forests and mountains of eastern Ravenland as theirs. When the Raven God divided the land, they tried to trick him, and as punishment they themselves were divided into halflings and goblins. The moonstones were torn from their breasts and according to myth taken to Aslene. Since that time, the halflings are shamed and desperately try to seem good-natured to conceal their legacy of deceit. The moon goddess Eor has become the goddess of lies, deception and hidden meanings, averting her face in shame every month.
The goblins are satisfied with their destiny. They still worship Eor with nightly rituals and sacrifices, as do the halflings although secretly. Among the halfling moon priests, some belong to the Penita – a sect dedicated to repentance. Its members seek the lost moonstones to restore their original kin. The goblins actively oppose this ambition since they’re fine as it is, but seldom kill halflings since they believe that each halfling life is connected to a goblin.