Can we get some more info on the Darkin?

Aatrox was released 2 years ago on June 13th (Actually my brother's birthday, so I have to decide: Celebrate my brother's or my favorite champion's birthday), and yet, very very very little is known about the Darkin. He has a backstory that isn't terribly small and actually, in my opinion, covers a lot about him. However, I would love to know more about the Darkin.

When they existed, what other types of races existed? What caused them to die off (Assuming they were immortal by age, which would make sense in my mind)? ARE they immortal by age (Can live forever, so long as they aren't killed by another source)? Who are the other 5 Darkin? Is Tahm Kench a Darkin? He's listed as an ally on Aatrox's page. Do the other Darkin look like Aartox, or do they all look very different? Are the Darkin actually the weapon, and the body is a possessed being? (This would fit Aatrox's title, 'The Darkin Blade', and it would also explain why Aatrox's blade is seemingly 'Living') Did the Darkin originate on Runeterra, or someplace else? If they did originate in Runeterra, where did they inhabit? Did they make cities and towns like other places seem to? Were they even civilized? Did they have a language? Did they have a religion? Are we EVER getting another Darkin champion?

These are just some things I would LOVE to know about the Darkin and Aatrox.

My grammar nazi self noticed that I used Who's instead of Whose in the poll. Please kill me.