[quote=@Raijinslayer]
[@Willy Vereb] Gotcha. Also, What is the physiology of half-elves like, and what would be the elf equivalent of 36-42, as that's the age range Celese, Silus, and possibly Navaea would be in. 
[/quote]Well, half-elves don't quite have an official physiology because it can differ per person.
Basically any combination of human and elven features are a game.
Techncally the success of human/elven pairings is just the matter of pure luck because it depends on genetical compatibility.
Not all elves can sire offspring with any human. Similarly some human genetic makeups are better fit for interbreeding.
Also while it isn't a general rule, a considerable portion of half-elves are born sterile.
Although an even larger portion of them aren't which is why Yllendthyr is growing more accepting to them.
They need them, otherwise the elven population would become a tiny minority in the swarms of humans.

Anyways, back to topic, half-elves are either just barely different from elves or they're humans with elven features.
This is for example a half-elven military commander:
[hider=Meneliad en'Zenthyr Daritsuoh]
[img]http://img01.deviantart.net/3613/i/2010/049/6/e/vasteel_heart___methos_by_kaijusamurai.jpg[/img]
[/hider]He looks much more bulky than what elves ever could be.
In a different era he may have been shunned and treated like the rest of the human slaves while being hated by his peers.
Nowadays this guy changed his name from the human-sounding Marzio to the elvish Meneliad and by sheer effort he became reclassified as elf and even gained a noble title.
Because as you know the Yllendthyr government officially doesn't recognize half-elves. So they are considered either humans or elves.

As for the lifespan of half-elves, it's kind of unpredictable. Some live less than humans while other can almost live as long a elves. The average is somewhere around twice of the human age.
So a 60-year old half-elf looks kinda like a 30-years old human.
As for what counts as 36-42 for elves.
I say around the age of 120.
100 could be said have the same meaning for elves as 30 does for humans.
If you aren't even 50 then you're really young in their eyes. Think of that as "collage age".
For reference the "age of maturity" is at the age of 30, which for pure blooded elves equal 13 years old in development.
And the equivalent of 18 years is at 42 for the elves.