Originally Posted by
Strategos
This is wrong.
In Warcraft 3 Illidan was specifically portrayed as a chaotic neutral character.
Knowing that the Well’s destruction would prevent him from ever wielding magic again, Illidan selfishly abandoned the group and set out to warn the high-borne of Furion’s plan. Due to the madness brought on by his addiction and the stinging resentment towards his brother’s affair with Tyrande, Illidan felt no remorse at betraying Furion and siding with Azshara and her ilk. Above all else, Illidan vowed to protect the Well’s power by any means necessary.
--Warcraft 3 manual