"That happened to the relevant faction of elves--or, well. Some of them. Eight of them. I don't know if there are currently any other Elves outside Valinor."

"Elves wanting humans to be immortal doesn't click the way some things you've said do."

"Well, my sister married one of them, and she's human, and they'd want us to be immortal even if they didn't care about the rest of humanity, but these are not normal Elves. I should possibly be less drastically oversimplifying in describing Elf politics."

"It sounds like it's something it would be useful to know."

"Okay, stop me and ask questions if I'm being confusing. So once upon a time Finwe was King of the Noldor--the Noldor being a particular nation or ethnicity of Elves--and his wife and Queen was Miriel Therinde. Unfortunately she got terrible postpartum depression after their firstborn son, Feanaro, was born, and ended up dying, and because Elves and death are weird her husband begged her to come back and she told him not yet, and he kept asking and eventually she got so tired of telling him to go away and leave her alone she said she would never come back so he petitioned the Valar to let him marry this other woman, Indis of the Vanyar--the Vanyar being another kind of Elf--and the Valar discussed it and the eventual verdict was that he could marry her and have more kids but it meant Miriel had to stay dead forever because otherwise a man would have two living wives. Because they had never heard of divorce, apparently. Anyway this whole thing took long enough that Feanaro was old enough to have an opinion on the subject, and he was understandably opposed to forcing his mother to stay dead forever."

"...okay."

"So Finwe and Indis have four more children, who are all perfectly nice in their own right so far as I know. Feanaro is never close to them because of what they represent to him, but their relationship is cordial. And all these children grow up, and Feanaro and his half-brothers Nolofinwe and Arafinwe marry and have children of their own.

Then Morgoth feigns repentance and the other Valar let him out of prison."

"...oh."

"Yeah.

So Morgoth pretends to play nice for a while, but all the time he's sowing discord between Feanaro and his half-siblings, arranging for rumors and whispers and essentially convincing both Feanaro and Nolofinwe that the other is scheming to have him disowned. 

And Feanaro is--he's a genius, he invented all kinds of things including writing, he learned both the languages I have from my original dimension in a single-digit number of days--but he's the kind of genius who's bad at people, and he knows it, and it leaves him somewhat insecure."

She nods. "How - old were they all? Thousands, right?"

"Technically, yes. Valinor has a weird time thing, so for practical purposes it was hundreds. Not that that's not stll plenty, but considering how they age..."

"So Morgoth set all the Elves at odds..."

"Okay, here I have to back up and explain some things. At this point, the world was flat, and had no sun. All the light that didn't come from the stars came from two giant glowing trees, and that only covered Valinor. So Feanaro managed to invent something that would replicate the Treelight. This would allow Elves to leave Valinor, since they could use them to grow crops, and also--Elves who've been exposed to Treelight long enough fade away after long enough without."

"Fade away?"

"Literally. If my friends don't--resist--they go translucent. One of them was only able to manage as solid as translucent for a few days, recently."

"Yikes. Is that why they're all gone - were there even survivors -"

"Well, keep in mind that this is only Elves who've been in Valinor, which is not all of them. We don't know if there are any other Elves surviving outside of Valinor right now, although apparently one of my sister's friends looks like she might have relatively recent Elven ancestry, so it's possible."

"Okay. ...I remember a sun."

"Yeah, I'm not done. So Feanaro invents the Silmarils, magic gemstones with the light of the Trees in them, and Morgoth sets him and his half-brother against each other, and things seem to be--tense, but likely to blow over. Towards the end of this period is when my sister and I showed up, and my sister married one of Feanaro's sons. And we all go back to Tirion, the Noldorin capital city, and Idaia and Tyelcormo--her husband--are adorable newlyweds at each other and get wedding presents from random passers-by whenever they venture into the city proper, and I get installed in the city and get started learning everything I can and helping reverse-engineer the printing press. Things are pretty great.

Then Morgoth tells people humans are going to happen, and shows prophecies about us. Some characteristic highlights that my sister and I recognized when we remembered them include European settlers slaughtering Native Americans, and the Holocaust."

"...how would he know..."

"Valar can get prophecies of stuff. No one knows exactly how it works."

"...okay. So they told the Elves about that stuff, and..."

"I recognized it as my species and Feanaro recognized that as my species and he immediately came to me and asked what a nascent humanity would need. We had already been planning to leave Valinor, but this brought it to a head. There was enough--disorder--over the question of whether or not it was a good idea to leave, that a hearing was called about it, primarily between Feanaro, head of the 'leave' faction, and Nolofinwe, head of the 'stay' faction.

And Morgoth arranged for Feanaro to hear from someone he trusted that there would be a serious risk of violence, so he should be prepared to defend himself. And before Feanaro even arrived, Nolofinwe, who had dressed exactly like their father the king, gave his argument for staying couched in terms that made it--unambiguous--that according to the argument, staying was Being On Finwe's Side and Feanaro was not that, and leaving was heresy against the Valar--not just unwise but immoral for its own sake--and ambiguous whether not disowning him was a wise idea. So Feanaro walked in with a sword right as he got to that part, and...

Well.

No one's saying it was good or wise for him to draw a sword on his half-brother, but he didn't actually hurt him and there was in fact kind of a lot of provocation."

"I see."

"So Finwe, who was fed up with the whole thing, chastised both of them and didn't disown anyone. Then the Valar decided to intervene. They exposed the lies that Morgoth had used to manipulate everyone, which prompted him to pull a runner, and then decided to exile Feanaro from Tirion for disturbing the peace. Half of Tirion, including Finwe, decided to leave with him, either because they were part of the 'leave Valinor' faction, or because they resented the Valar's intrusion into Noldorin matters. We traveled north, and built a city called Formenos, and tried to figure out how to leave--we didn't know how to build ocean-worthy ships, only the Teleri--another group of Elves--knew that. And the only way out of Valinor was across the ocean or across the Helcaraxe, which in its modern form is the extreme northern Arctic. And we didn't have cold gear as good as modern stuff.

At one point Morgoth showed up and offered to help build ships but considering how deeply untrustworthy he had proven himself Feanaro cried, 'Begone!' and slammed the door in his face."