Other Races
The drow don't wander the deep reaches alone. There were several races here before the drow arrived, and they will very likely remain after the Return.
Goblins:
Can only charitably be called sentient. Mostly they are an undisciplined swarm of filthy, cannibalistic murdering scum. They fear horses and dogs, and are inordinately fond of fire. Not that they’re any good at controlling it, frequently setting themselves or their fellows on fire (they find this hilarious). They tend to be as much a danger to themselves as others, but in numbers can overwhelm even a disciplined patrol.
Underhollow drow deeply hate and loathe all things goblin. The Goblin Wars that the last generation faced are still remembered in story and song, and the walls of the City of Embers still bear the scars of those battles. No goblin would ever be welcome within the Underhollow.
Obsidian Warren drow have discovered that goblins respond well to pain and fear as teaching tools, and so use them as the bulk of their slave labor. Goblins make particularly useful shock troops, and more than one house has been saved from a raid simply by unleashing their legion of goblin slaves on the unwary intruders. Enslaved goblins fear all drow, but the whips of their Matron and her daughters are the most terrifying thing of all.
Nomadic drow hate and fear goblins, who descend upon camps in the night and devour everything vaguely edible (including still-screaming drow) before vanishing back into the dark of the tunnels.
Orcs:
As far as most drow are concerned, an orc is a damn sight better than a goblin, but still not very bright (or so the prejudice goes). These fierce warriors roam in mostly-patriarchal nomadic tribes that war on one another constantly. This tendency towards violence and an admittedly primitive lifestyle has led the drow to assume them to be thickheaded, hot-blooded numbskulls. They have thus far (as a culture) failed to notice that the orcs are, in fact, deeply spiritual. They just happen to believe that one’s worth is best determined by valor in battle, be it against the beasts of the caverns or one another.
Underhollow drow would prefer to avoid orcs, but won't turn down trade if the merchandise is sufficiently tempting. Orcs trying to pass through the Silverweald are often harassed by patrols, but the orcs seem to genuinely enjoy these little tiffs and usually nobody dies.
Obsidian Warren drow love a good, strong orc. They're difficult to break without killing them, but once that's done they're great for work that requires heavy lifting (somthing goblins, even working in concert, are terrible at). They also make fantastic pit fighters, and watching small groups of orc slaves battle to the death is a favorite sport in Cissilith.
Nomadic drow and orcs do not get on. They compete for the same space and resources as the orc tribes, and the orcs are much larger and stronger than even the most powerful drow warrior. Alliances are rarely struck, but when they are the drow's superior knowledge of alchemy and herbcraft and the orc's superior strength makes the alliance a potent one.
Dvergar:
These fellows are dirty, gruff, and generally cranky. They are short and gray-skinned, almost appearing to be made of stone. The dvergar have cities of their own, hewn into the living rock and nearly impregnable even by bandersnatch cavalry. They’re much better at metallurgy than the drow, and trade with them is the main source of gemstones and finely worked metal goods.
The Underhollow drow have even even formed some loose defensive alliances between themselves and nearby Dvergar settlements. Dvergar and low-caste drow tend to get on fairly well, but the middle and upper classes tend to find them crass and unrefined at best.
The Obsidian Warren welcomes dvergar artisans whenever they can find them (whether the dvergar artisan likes it or not) and honestly they're treated fairly well for slaves and non-drow, as the only thing a Matron loves more than a flawlessly-planned murder is something beautiful and sparkly to wear while she's twisting the knife.
Nomadic drow often trade with dvergar settlements for metal goods (which they don't have a prayer of ever making themselves) and supplies in exchange for information on mineral deposits or rare reagents for smithing.
Ogres:
Tall as a single-story building and nearly as clever, ogres roam the deep reaches in herds of ten to twenty individuals. There is little to be done to prevent something of an ogre's size and strength from rambling into an area and grazing it bare, and if threatened they make formidable foes.
The Underhollow drow have little love for ogres, as it was a particularly clever goblin tribe enslaving a tribe of ogres that led to the Goblin Wars in the first place. However, all but the most unreasonable Underhollow denizen recognizes that ogres are far too stupid to truly be to blame for the altercation.
Cissilith drow, on the other hand, value ogres for their strength and the ease with which they can be addicted to and manipulated by khu'rush, a preparation of several commonplace herbs together with an extract of the blood of a particular species of crab (also quite common) that ogres seem to find especially palatable. Khu'rush has the effect of dulling the intellect to a point, but especially the parts of the mind that form arguments and question assertions, making those affected by the drug astoundingly biddable. It is also highly addictive, but drow are largely immune to its effects. Males are more susceptible than females, which is sometimes pointed to as proof of male weakness.
Nomadic drow just try to avoid ogres as much as possible. A few cases of symbiotic alliances (if a partnership with something that dumb can be called an alliance) have been seen, but they are rare.
