Originally Posted by
EnigmAddict
no, as far as I know, some of the night elf demon hunters can be thousands of years old, not sure there, but for the blood elves, this was after blood elves joined Illidan in WC3 TFT, and you get to see Illidan start accepting blood elves as demon hunters during TBC. But I think the book Illidan implies all demon hunters NElf and BElf started after Illidan's release and the 3rd war, so these are people, esp NElves that saw the horror of the demons and dedicated their lives to fighting them. IT is hinted by Altruis in Nagrand, that some of the blood elves might be more concerned with gaining power than stopping the evil, at least when referring to Vareidis, but it is a characteristic of their race - Demon hunters are actually pure hearted despite the dark things they deal with.
and this is probably why they get accepted later on, because in Legion the races get to understand that a few exceptional individuals actually have chosen to bear the burden of fel for power but remain pure of heart in their intention to rid the world of demons. Now their struggle might endear them to be tempted by power and even grow to love power, but despite this ultimately their goal is to see the down fall of the Legion to save their people.
There seems to be a distinction between the deep fervour of the Demon Hunters that is not letting them get all twisted like say Arthas did. again, i.e. Pure heart - but saying that, not all demon hunters last, and well some can give in and lose that struggle at any moment - so you must always be watchful around them.