I don't know what point you're trying to prove here. Fel magic does exists in the Nether.
Eh, the difference between fel (the language of chaos) and arcane (the language of order) seems to be a difference established by opinion rather than fact. We definitely have the arcane user Iyyokuk the Lucid claiming Chaos is order unrecognized by a lesser mind!
Fel can be considered volatile and I'm just curious as to why arcane (order) pervades a place stated to be beyond the limits of order in one of the War of the Ancients novels.
I'm pretty sure fel does pervade the Nether
Fel magic does exist in the Nether.
If demons contain fel magic, they can be considered a source of it - which is why I don't like the fact that Sean Copeland claimed demons aren't the source of fel magic.
It does exist in the Nether. If demons contain fel magic and demons are in the Nether, fel magic exists in the Nether. Of course fel magic naturally exists in the Nether if demons are born there.