PHB, Homebrew, MotM
Half-elves are typically rare in most of Cisum, but the they are slightly more common amongst the islands of the Acapellago. Often seen as outcasts in both human and elven society, half-elves typically find solace in the island chain. The slight differences of the island elves make half-elves more readily accepted and common in the region. Having to keep a foot in both the human and elven lives makes half-elves great diplomats. When they are born or grow up in a region that shuns them, they often turn to adventuring as a way to find purpose.
If playing with achievements and milestones, choosing this race at character creation grants the player the achievement "A Place For Us."
Darkvision. Thanks to your elf blood, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.
Fey Ancestry. You have advantage on saving throws against being charmed, and magic can't put you to sleep.
Skill Versatility. You gain proficiency in two skills of your choice.