Half-Elves
A Half-Elf belongs fully to neither parent’s world: too short-lived for the elves, too strange and slow to age for the humans. Rather than mourn this, most Half-Elves have made a culture of it. If you inherit no home, you choose one, or you build your own.
The go-betweens
This makes them the realm’s natural translators, envoys, brokers & guides, comfortable being slightly foreign everywhere they go. A great deal of the realm’s inter-continental diplomacy and trade quietly passes through Half-Elf hands.
Friction
Belonging to everyone means belonging to no one. Half-Elves are trusted to mediate precisely because they are assumed to have no side, which is also why, when a deal sours, both sides find it easy to suspect their loyalty first.