City of Brass
In the City of Brass, half-orcs are not an orc/human hybrid. One half is orc, sure, but the other half is giant ant.
The hordes of swarming orcs that roam the desert live in symbiosis with a clever species of ant colony. Over the aeons, some magical thing happened and the races started to merge. Arcane experts think it has something to do with the process that creates a queen ant, but really, no one knows.
A giant ant colony in the desert consists of an equal division of orcs and ants, and a small number of half-orcs.
A half-orc looks like a slightly smaller orc with a harder skin and antennae where horns would usually be. Their faces are less swinelike and pointier, and some of the race have small mandibles or antlike compound eyes, or both.
Half-orcs in the City often yearn for the safety of a large group, as they miss their colonies. Half-orc barbarians often find their way to the City of Brass; their chaotic natures make them a bad fit for the order of colony life and they often leave as outcasts.