(If I'm forgetting anything or you want to know about anything, ask me in the comments and I'll post it and the answer in this chapter)

~Looks
(Physic)
Drow elves are often described as being towering, powerful beings. Most have dense, powerful muscles that often shows due to their genetics, even with little effort to look that way (yes, even females). They average at about 7 foot but can grow much taller, the tallest on record being 10'11. They often have black skin, though that can range to a dark grey or even different shades, including but not limited to purple, brown, and even blue.

(Hair)
Silver hair is to drow elves as brown is to humans. While striking to most outsiders, silver hair is common to drow elves. That can range, however, often to red, brown, white, black, and gold, on rare occasions. Golden and blonde hair are rare among drow elves and often seen as a symbol of good fortune. Their hair is usually straight and most males keep it short, much like humans on the surface.

(Eyes)
Again, silver is to drow elves as brown is to humans. Their eyes have a much greater range in color, ranging from silver, white, purple, yellow, and orange as more common colors, to blue, green, golden, and white as rarer colors. The color red is hardly ever gotten naturally, and is usually seen as a bad omen if it is. Drow elves with red eyes, or red coloring in their eyes, usually suffer from broken Bonds from past mates.

(Ears)
Their ears are pointed, much like other elven races. However, instead of long and thin, they are shorter and broader, much like a bat's ears. They are highly sensitive to noise, much more so than other elven races or humans. If a drow elf hears something and you don't, it would be wise to listen to them.

(Other Features)
Drow elves are known for their demonic qualities, including their sharp teeth. They have sharpened canines on both jaws. Many are often mistaken for demonic vampires due to their length by humans, leading to many myths and tales.

(Rare Features)
Starting with the ears, a rare and highly attractive trait to them is a scalloped edging, where instead of being straight, the bottom edge of the ear is slightly waved. Moving to eyes, blue, green, golden, white, and red are rare and striking colors, though not all are seen as attractive. Red is generally a sign of danger about who, or what, they will become. Golden and blonde hair are just as rare and attractive as the scalloped ears, usually a sign of luck.

~History
Drow elves are actually a breed of half elf, between a Forest or High elf and a demon. Over so many millennia, they evolved into their own species separate from both. The first few original Drow elves were killed, due to the elven distaste for half elves or to the demonic forces hatred for elves. A few, however, survived.

The few that survived banded together and hid within the mountains with the dwarves. While not liked by them either, they were stronger than their elven parents and helped with the mining and forging of precious metals. While they helped the dwarves, they sought out other half demon, half elf halfbreeds.

The elves weren't very fond of this when they figured it out, many centuries after the first few vanished. By then the demonic half breeds had grown in number to be a decent threat. And since they had grown into allies, and perhaps even friends, with the dwarves, that didn't bode well for the elves.

A single massive, bloody war that lasted for centuries was waged between the drow elves and dwarves, and the surface elves. The surface elves were skilled and graceful, but the drow elves had the strength of a demon and the anger of a half elf. And with the dwarves on their side, the fight was an even one.

The bloody war ended in a draw and a 'treaty'. This treaty made an uneasy peace with the surface elves and the dwarves, at the drow elves' expense. They were forced below ground into underground caverns, thought to be away from anywhere that could do any harm.

Most drow elves perished to the dangers of the underground world (or as its now known as the Underdark), from massive and venomous Cave Vipers, to Giant Bats, The Elfmuth, the Giant Spiders, and their lack of adaptations to survive. They were adapted to the surface world and the light, not to the pitch black. Their infravision helped and allowed them to survive at all, but it wouldn't save them from everything.

They devolved into primal beings that fought like animals to survive. Fighting with their teeth, nails, anger, and brute strength, they survived. They evolved their dense bones to survive cave ins and blunt force trauma. They evolved their dense and powerful muscles to move stone, rock, and each other when they had to. Their infravision evolved, allowing them to see as if they were on the surface. They no longer saw in shades of hot in cold, but genuine color again. They grew a resistance, and then immunity, to all but one type of poison to survive the deadly creatures that dwelled with them.

From there, they grew out of their primal ways. They reformed a government and built towns, and then cities. Millennia had passed before they completely shed their primal ways, and many of their adaptations still hint at their savage past, but they now survive as most surface dwelling races would.

~Adaptations
(Night Vision)
The Drow elves originally had infravision, much like most surface elves. When they were sealed away underground, that slowly evolved out of seeing patches of hot and cold into powerful night vision. They can see in pitch black as if it were day, giving them a huge advantage in the dark. However, their eyes won't adjust back to the light without assistance or training.

(Extending Teeth)
The sharpened canines of the Drow elves actually extend in times of extreme stress or emotion, like the claws of a cat. This was to help them pierce skin and flesh when they were savage survivors. This has yet to devolve in them.

(Sharpened Hearing)
Their hearing is better by leaps and bounds than any surface dwelling race. They can often tell when a natural cave in will happen due to this, and it has saved their lives many times in the past. Now, it's generally used to tell when a mine is about to collapse.

(Dense Bones & Muscles)
The Drow elves evolved dense bones and muscles to survive cave ins and to fight off enemies. Their bones are 8x as thick as a human's bones, which would allow them to survive a car crash with minimal injuries and much higher falls. Their muscles are wired around these dense bones to give them supreme strength, rivaling the physical strength of a demonic being.

(BloodLust)
Their most dangerous adaptation is called BloodLust. There are three stages of BloodLust. The first is just regular anger, where their pupils turn into slits like an angered cat. The second is where their teeth lengthen, and they get a strength and stamina boost. The third is their most infamous. The whites of their eyes become red and misty, their strength and stamina increased greatly. In the third stage, they feel no pain and often bleed out before they come out of it. They won't come out of this state until whatever angered them is dead, gone, or they're put to sleep. Many drow elves have died due to their own or someone else's BloodLust.

(Bonding)
The Bond to a Drow elf is similar to the Mate mark of a werewolf or a dragon. It's a light swirling pattern that covers the entire hand and forearm, trailing off at the elbow. It allows one to feel the other's pain and emotions, and is the only way a Drow elf can mindlink. If broken for any reason, it tears out a piece of the Drow's soul and leaves them screaming in agony. A red rim would surround their eyes, usually bright in color. It depends on the Drow, but if the Bond is broken too many times it will kill them.

~Magic
(Runes)
Runes are the only way a drow elf can do magic at all. Runes can be used in place of any spell if the caster (or wearer) is skilled enough and has enough energy. At first, only simple runes were used, but through experimenting, the drow elves now create their own runes to use. They drain the energy of the wearer or caster, and if they don't have enough, they can pass out or even die. The runes marked on the wearer glow in use, and glow the same color as the caster's eyes.

(Runeweavers)
Runeweavers are the Drow elves that specialize in using runes. They tattoo their bodies with runes for simplicity's and aesthetic's sake. The runes often strip them of any excess calories they have as energy, which usually leaves them drained and hungry. Runeweavers, unlike most other drow elves, are thin, lean, and compact due to the way the runes work. Together, Runeweavers can do powerful and frightening things with the runes they use. That includes splitting someone else's soul in half, which they use in only dire circumstances.

(Shadow Jumping)
Shadow Jumping is their way of teleporting. They use shadows as doorways to other places, or even other people. It has limitations, as Shadow Jumping drains energy as well. The person has to know where, or near where they're shadow jumping. If they're going to a specific person, they have to know the movements of their shadow; if they're energetic and animated, or still and silent, or anything else. They're more likely to shadow jump to a place rather than a person, unless that person is a close friend or a family member.

~Government
(Emperor & Royals)
The Drow elves are led by a single Emperor or Empress, or both. The eldest child, not son, takes the throne when the parents retire and pass the crown down. However their court has a massive sway over what they say and do, as most of their funds come from their court. Losing even a single royal could be a huge detriment to whatever they're trying to accomplish.

(Gold Mines)
The gold mines are where slaves are kept to mine for the gold that the cities use for currency. Most slaves are usually criminals, such as murderers and arsonists, though occasionally someone from the court is bribed to put an innocent person in those gold mines. Most times, those who go into the gold mines don't come out alive.