Bloof Elves and Fel Magic...

[Aoto]

So, from a RP-perspective...what is the average Belf's (mages, pallys, etc) relation/interaction with Fel-magic? Is it the cause of their sub-race's unique green eyes (as opposed to the other sub race's blue eyes)?

And just what are the green crystals in Eversong?

[Eldonius]

The average elf had, prior to the events of the end of the Burning Crusade and the reignition of the Sunwell, little to no contact with fel-magic. I'd assume that after those events the probability of them using such kind of magic has reduced even more.

We have several evidences pointing to the conclusion that the green crystals we seen in Eversong Woods and Silvermoon City itself are just Arcane Crystals, called Burning Crystals by the Blood Elves themselves, used for storing such energies and have little to nothing to do with Fel magic itself (despite the eyes staring back at you in some).

Regarding the green eyes: The most important thing o understand here is that fel magic is a potent, but extremely corruptive, source of magic. I have two theories as to why the Blood Elves eyes turned green, even the eyes of those who did not directy consume stolen magical energies.
One concerns the Burning Crystals - even though we have been told they're not demonic or evil in nature, if stolen energies with such "color" were deposited in them for the citizens of Quel'thalas to be empowered from, it would explain why their eyes turned green, even if they didn't directly drain it from the crystal.
My second explanation uses the orcs as a basis. We know for sure that not all Orcs drank the blood of Mannoroth, and were thus forced into a Blood Pact, but yet the majority of the orcs changed their skin to green. Familiar thing could be happening to the Blood Elves. Those Blood Elves who stand in the vicinity of fel-users or -consumers, would still get the green eyes by being "irradiated" by the energies these handle.

[Lamainiel]

basicly Eldonius explained most of it. to understand more of Belf backstory you need to know their origin.

Belf were once known as high elfs, as nightelfs who are able to control and use magic. after the well of eternity event occurs they left the nightelf society and went to eastern kingdom. They got their green eyes during the events occured in frozen throne, as kael'thas brought 90% of the population to outland. ( basicly we played as the minority 10% who got left behind) The got corrupted by consuming fel magic and got their green eyes.

for accurate role playing. There is a small part of the lore that mentioned about the crystals in eversong forest. it have been moved, as staying around it isnt healthy for the ecosystem as well as for the bloodelfs. if u ever think that it look outlandish, you are semi correct about it, althought without any lore backing it up for its appearance, but it still written as the crystal as were there before the elfs.

and now the story reached WoD. there is cases of blood elfs cleanse from the fel magics, the paladins first as their power mainly come from the naaru / light. with their fel magic gone the blood elf will have blue eyes ( you can find some of those un corrupted blood elfs in stormwind or dalaran.

have fun :D

[Eldonius]

Furthermore, what is important to understand is that you can Roleplay a Blood Elf that hasn't got green eyes too.
Given how being a Blood Elf is more of a cultural thing instead of a racial one, as Blood and High elves are essentially the same species, just having green eyes doesn't make you a Blood elf. It's about the way you think and view the world that does.
Also, we have evidence that a blood elf's, and probably a high elf's, eyes can briefly change color depending on the source of magic they just fed upon. Example for this is Valeera Sanguinar whose eyes turned purple after consuming some druidic energy if I'm not mistaken.

[Vipond]

Eldonius pretty much covered it. Essentially, blood elves and high elves are physiologically identical (as explicated in "The Shadow of the Sun" short story, available on Blizzard's site). However, prolonged exposure to fel magic has been known to manifest in different ways, most notably the green skin of most orcs. The existence of blue-eyed elves (otherwise known as quel'dorei/high elves) arises from a small percentage of the elven population eschewing any association with fel magic. Such individuals are typically treated with animosity and contempt within Blood Elven society, sentiments that the quel'dorei readily reciprocate.