"Think occasionally of the suffering of which you spare yourself the sight." - Albert Schweitzer
The Dark Eldar are the villainous counterparts of the Eldar, who followed the horrific depravity that saw the Eldar Empire destroyed. Hailing from Port Commorragh in the Webway, the Dark Eldar spirit out from the shadows to take slaves to commit unspeakable atrocities on whoever they capture.
In short, they're the most evil race in Warhammer 40,000, which is a hell of an accomplishment. Their lives revolve around sadistic torture, making them a sort of cross between the cenobites from hellraiser and the reavers from fireflly.
The Eldar, after the disaster that caused Slaanesh and turned their empire into the universe's biggest Goatse.cx reference, destroying their once-great race and killing 90% or so of their population outright, were a dying race. Slaanesh was devouring their souls like Eldar McNuggets, and it was only through ascetic mysticism and use of Soulstones that Eldar could avoid getting nommed by She Who Thirsts. Conventional wisdom was that these Eldar only survived on craftworlds and maiden worlds that the Eldar had colonized before the fall.
Conventional wisdom, of course, means little in the 40K universe. Whilst most of the Eldar were assraped to death by Slaanesh when their falling into depraved cycles of decadence reached critical mass and caused a Chaos god to be born, a few of them survived because they were in parts of the Webway (a portal network that the Eldar use for transportation). They escaped with no real ill-effects, or so they thought. In reality, Slaanesh was slowly nomming their souls just like she does every Eldar without a Soulstone - however, they found that by continuing to engage in rampant hedonism and by torturing and inflicting pain and anguish on other creatures would reduce or even the reverse the effects of Slaanesh's hold on them, forcing them to seek out and capture, kill, and torment the "lesser" races of the galaxy in order to satiate themselves and stave off their doom. Some claim that this was Just as planned by Tzeentch; some scholars hint Eldrad may bear some responsibility (although seeing how he was a rookie seer at the time doubt it).
Sadistic and psychotic to the point of making your average Chaos Marine look like hippies in contrast, hopped up on cocktails of combat stimulant drugs that would OD an Eversor, and armed predominantly with weapons and equipment that cause unspeakable immeasurable agony in those they go after, the Dark Eldar are easily the most depraved and vicious race the 41st millennium has. Hated by literally every single faction in the 41st millennium, the Dark Eldar are perhaps the only race with bigger assholes than Eldrad, though in spite of this, unlike their sissy counterparts, the Dark Eldar are hated much less by the playerbase - presumably because their army actually takes some brains to use and isn't a giant bunch of status-quo-defending faggots. Well, that and its implied they use sexual torture along with the normal kind.
In battle, Dark Eldar center around hit-and-run tactics, dealing huge damage and moving fast; few of their units can really take much abuse, making them even more fragile than their counterparts. Their standard infantry armor is identical to that of a Guardian (not terribly good), their vehicles are predominantly lightly-armored transport and attack craft that can be brought down by anti-infantry gunfire, and the armor on a typical Wych or Grotesque is no tougher than the ramshackle metal plating favored by Orks, but without the whole "I believe this armor will protect me, which is why it does" and at absolute best will cover only nipples and vulva, meaning that it would take considerable skill (and a somewhat sadistic shooter) to bounce a round off of their 'armour'. Suffice to say, they are extremely fragile and metaphorically half-naked in battle (literally if female), and getting the most out of them takes skill and patience that is rarely-seen on /tg/; whilst most fa/tg/uys will openly mock your average Eldar player, they will give pause and show some respect to a Dark Eldar player worth their salt.
The Dark Eldar are known for the excessive amount of fapping material involved with them, and they are the subject of thousands of sexual fantasies by
desperate masochistic teenagers middle aged neckbeards incapable of handling real women. They did, after all, kind of rape/drug/kill/etc themselves into oblivion, which tends to lend itself towards certain excessive abuses. They are also known for having some of the most fucking awesome-looking models on the tabletop, even if the armor of half of what they field will suffer instant critical existence failure at the hands of your typical Space Marine.
As someone lost to the annals of history noted, the fact that the Dark Eldar are ambitious, sex-crazed, easily shot down, boat & airplane loving pseudo-aristocrats haunted by a terrible curse means that they are the 40k version of the Kennedys.
The Dark Eldar, historically, have always been the race for the professionals; they were insanely hard to use by any stretch, their units too lightly-armored, their models requiring some expertise to pick up without impaling yourself, and they were easily the least played faction in the 41st Millennium. Nearly 12 years passed before a codex update - and suddenly just recently (2010), GW decided to throw the Dark Eldar players a much-needed bone.
Sweet Jesus, talk about buffs.
Very little changed fluff-wise, though a lot was fleshed out, but the Dark Eldar gained substantial staying power and can actually field a reasonably
tough hard-hitting army now. Their new Power from Pain rule makes them tougher as they score kills, and the army now has a lot of potential for being much more forgiving of mistakes (previously it was a case of either steamrolling foes or getting curb-stomped). Lots of new options and extensive access to poisoned range weapons makes them extremely versatile - as well as the bane of Tyranid players everywhere.
The Dark Eldar Themselves
"I came to bring the pain, hardcore from the brain/Let's go inside my astral plane." - Method Man, Archon of the Wu Tang Kabal.
The story of the Dark Eldar's fall and their need to inflict pain and horror in order to live - as well as elaboration on their kabalistic practices - have gone a long way towards deepening their fluff considerably (as one noble fa/tg/uy surmised, less retarded Saturday morning cartoon villainy). While some have balked at the more vampiric flavor of the New DE Codex, several denizens of /tg/ have managed to extract comic gold from this. A common musing is that they are ambitious, sex-crazed, easily shot down, boat-and-plane-loving pseudo-aristocrats haunted by a dark curse - ergo, they're not vampires, but, in fact, the Kennedys.
Putting it simply, the soul of a Dark Eldar is an open wound that can only be salved with suffering, a void that can only be filled with tortured bodies, a thirst that can only be quenched by spilled blood. The origin of this void within the Dark Eldar, and the source of the nigh-religious terror that drives them to commit these daily atrocities, is the knowledge that
THEY WILL NEVER BE ULTRAMARINES upon death, their soul is forfeit to the Chaos God Slaanesh - an eventuality they intend to stem off at all costs.
Fortunately for the Dark Eldar, provided that someone recovers enough of their remains, their dead body parts can be brought to the Dark Eldar Haemonculi (an ancient order of Dr. Mengeles, the people that educated Fabius Bile in the art of being a gigantic dick) and regenerate themselves in case of death, complete with personality and mental faculties intact. This also keeps their soul from being devoured by Slaanesh - but at a price - this regenerative process is fueled by pain just as surely as the Dark Eldar themselves. This is the reason Dark Eldar raids are so eager to get in and get out as fast as possible; if the subject is dead for more than a day or so, they're beyond recovery.
Their diet of anguish has blessed the Dark Eldar with some of the longest lifespans in the setting, only surpassed by godlike figures like the C'tan, Necrons, the Emprah, and the Chaos Gods. If they die, they just respawn back at base once the Haemonculi have managed to torture and/or bosh enough pain out of their subjects to allow the occupants of their rejuvenation pods to regenerate.
The Dark Eldar have also overcome the traditional Elven birthrate problem by finding a fun workaround to the long gestation period of conventional Eldar - they can remove a fertilized ovum and place it in an amniotic tube to age them quickly enough to be useful. This is looked down on by Dark Eldar society however - they even have an elite unit, the Trueborn, that are basically a bunch of spoiled brats who feel entitled to all the good weapons just because they got pushed out of a proper twat. The fact that hedonism is the rule in Commorragh probably helps too. On that note, Dark Eldar society has a MUCH larger population of Eldar-human hybrids than anywhere else. What, you thought human slaves were only there for toil or torture? (Although rape by a Dark Eldar involves both of these things, so don't get your hopes up.)
The Dark Eldar have some of the most advanced tech in the 41st millennium, in cases even surpassing the powerful weapons of their cousins. Access to weapons that basically fling incandescent dark matter and miniature stars around goes a long way towards giving them serious "I'm going to fuck your shit up" power, and their access to arcane wargear and super-fast vehicles even more so. In fact the only race that comes even close to the technological level and destructive power of the Dark Eldar is the Necrons, whose basic weapon rips the molecules off its target, flaying one layer off at a time (though it's still near-instant). Humanity apparently managed to one-up them back in the Dark Age of Overpoweredness, but given that applies to every other race as well (including Eldar) and they've forgotten how to use any of it, that hardly counts.
All that said, at least now their continued survival is not as implausible as the Reavers from Firefly maintaining a functional spacefleet - the Dark Eldar are smart, and even though they'll fight each other to death over a biscuit in Commorragh, during a raid into Real Space they set aside their differences to GET SHIT DONE. The new codex also points out the Dark Eldar do follow a set of rules while fighting each other and running shit, one of the reason they they enjoy to raid real space is because it allows them to cut loose.
COMMORRAGH WELCOMES CAREFUL DRIVERS
The Dark Eldar live in the Dark City of Commorragh, basically an impossibly large extradimensional port city fueled by two stolen suns (and they made sure to steal suns from inhabited planetary systems, because fuck those guys). Think of a sprawling cross between 17th/18th Century Shanghai/Singapore/Port Royal with Mos Eisley space port , a wretched hive of scum and villainy with a drug/torture/rape-based economy and the warped architecture of Inception. So watch out, Utica! Commorragh is a city on the... Grow!
If you can survive the inhabitants of the Dark City there is only one problem. Being in the Webway, every now and then the Dark City will suffer something called a Dysjunction; the Webway/Warp equivalent of a natural disaster which is a more powerful combination of earthquake/firestorm/hurricane that can spread across large parts of the Webway and really wreck Commorragh. In addition, it damages the walls of the Webway, which can allow daemons to invade all across Commmorragh. Fortunately, this is rare and only happens during huge bouts of Warp-related turmoil.
It's only been invaded once by Orks (that time with daemons, apart from Dysjunctions, they were summoned into Commorragh) and the only time it was in serious danger was when Vect, plotting a coup against the ruling Archons, arranged for a ship filled with a few hundred Space Marines (In a shocking change from the norm, the Salamanders, for once; Matt Ward is rumored to have had the vapors from this, though the Salamanders are frequently depicted as having a huge grudge against the Dark Eldar due to Vulkan's origin story) to be towed to the Dark City. Of course, most of Commorragh's armed forces fought the Space Marines, who managed to escape despite heavy losses.
Five-hundred combat equipped Space Marines in a close defensive formation were barely able to hold back the Dark Eldar long enough for reinforcements from other chapters to arrive (Vect deliberately left the webway portal open to allow this). Bolstered with these reinforcements, they held out long enough to free the initially-captured ship and escape, and lost well over half their number doing so. All the while, the Dark Eldar counterattack was impeded by Vect's battlefield assassinations of important Kabal leaders and stalling of reinforcements from the rest of the Houses until the people he wanted dead were dead (notably, Lelith Hesperax led the charge on one of these assassinations, demonstrating just how old she is). Does being manipulated into a frantic and losing fight for survival to further the political goals of a Dark Eldar sound like the hallmark of Matt 'Khornate Knights' Ward? Nope. Salamanders are awesome, Asdrubael Vect is awesome, Phil Kelly is awesome, this codex fucking rules.
At least the Dark Eldar actually have playable special characters now:
Asdrubael Vect, the Pimp Master General of Commorragh who's now a manipulator on par with Eldrad and, impossibly, an even bigger dick.
Drazhar, the Master of Blades, who's strongly suggested is the fallen Phoenix Lord of the Striking Scorpions aspect.
Lelith Hesperax, an oversexed gladiatrix/snuff-film porn starlet so badass her fucking hair counts as a power weapon (srsly, so much implied masturbation in her profile, it's not even funny).
Lady Malys, an anime villainess and Vect's pissed-off ex-wife. She won someone's heart in a contest and shoved it in her chest.
Kruellagh the Vile, possibly the worst-named character in 40K history. NO LONGER EXISTS. ALL HAIL LORD KELLY!
Lord Hellion Baron Sathonyx, who many on /tg/ believe to be Spider-Man's archnemesis.
Kheradruakh the Decapitator, who, uh, cuts peoples heads off and collects them like beanie babies. Implied to be collecting them like coconuts to do some serious warp-related shit.
Urien Rakarth, a hyper-evolved Pavi Largo.
Dating a Dark Eldar
Buying this CD is Heresy! Download it from torrent.
Your daily commute in Commorragh, except everyone's an elf-rapist, the pistols shoot poison that can kill robots, and the chicks are soul-sucking crack whore gladiators.
Fucking Pony nonsense... Fucking with... Sense of... What were we talking about?