The Fall of the Eldar

I am not entirely sure whether or not this question/forum belongs here but I am going to ask it anyway, what exactly happened during the fall? of course there is a general constants that slaanesh was born and killed just about every eldar including creating the eye maelstrom but what lead up to that point? were there any texts or books that tell the tale of the fall? is it only just legend? or was it just a giant orgy? If anyone could help me out would be great.

More or less a giant Orgy, yes.
With amish i mean exodites leaving the party first, going to the maiden worlds, then the craftworlders, many too late though, dying.
And we just party on in the Webway, our Dark City being the main hub.
Rather safe from Slaanesh.
Unless we stop partying of course...

THE HUNGER!!!

Also this probably belongs in the Background section.

The book Asurmen: Hand of Asurmen has a number of passages leading up to, during and just after the Fall, although it's set on a world that's outside the core worlds of the Empire so the excess isn't quite as pronounced (apparently the core worlds were where it was worst, outside of the webway that is).

I haven't read the book myself, but I don't think it was an instant thing, although it was pretty quick. Things like daemons possessing the corpses of recently-dead Eldar and using them to attack the survivors, and proto-Dark Eldar striking out from the webway to prey on them too (one of them even has wings grafted onto them, indicating that the technology to make Scourges was developed prior to the Fall).

What would a follower of Slaanesh do?
assault, torture, mutilate others and himself, sacrifice, etc.
That's basically what they did.

One thing about the Chaos gods that everyone seems to forget (including the writers themselves it feels like) is that they stand for things other than grimdark death and destruction.

Khorne is the god of honor and nobility and bravery as much as he is fighting and war.

Tzeentch is as much about inspiration, hope, and understanding as he is deception and despair.

Nurgle is essentially nature incarnate, without him there would be no cycle of life, no growth, no decay, etc. Of all of them he's probably the best represented in this way.

So of course Slaanesh is more than just murdering and torture for the thrill of it. He/She/It is about all strong emotions, so intense joy, sadness, anger, excitement, lust, fear, love, etc. Pre-Eldar society wasn't just corrupt, it was hedonistic. The sin the Eldar committed was worship of themselves in the literal sense. They were always the most important, and whatever made them feel new intense emotions is what mattered more than anyone or anything else. They were like junkies always chasing that next high. That "next high" turned out to be the birth of Slaanesh, which consumed them mind, body, and spirit.

Absolutely. I've always thought that the Chaos Gods represent a whole breadth of things, and it's only the completely fethed up nature of the 40k universe that means their grimdark sides are the strongest. I've got a bit of headcanon, for instance, that Nurgle probably started his existence as a fertility god and through the horrors of the galaxy has been twisted into the form we know now.

It's something I'd really like to explore in some of the fluff I'm coming up with. The fact that life under the Chaos Gods isn't necessarily worse than the Imperium...just different (this being 40k of course, they're both pretty horrific).

Two ideas so far:

Spoiler:

Extreme emotions. Well said. And they figured that emotions like fear, Lust etc are much easier to trigger than love or joy.