The Netherwing Dragonflight are ruled over by Neltharaku AHT and his mate Karynaku AHT. Their faction is not fully implemented in the Burning Crusade, but there is a quest line that will get you up to Neutral status with them. It is known from official sources that a superfast Netherwing Drake mount will become available through some kind of quest route: though it isn't known for certain that Nethering faction will be involved in this, it's hard to believe that there'll be no connection.
Gaining Reputation
There is only one way to gain Nethering faction at the moment, and that is by working through a quest line that starts with Mordenai AHT, who wanders the Netherwing Fields in the southeast of Shadowmoon Valley. Complete his quest, Kindness AHT, to start a chain that will lead you ultimately to release Karynaku from the Dragonmaw TW Orcs and (more importantly) gain a huge boost in reputation that will move you to Neutral with this dragonflight. Most of the quests in this line are quite soloable, except the final one, Zuluhed the Whacked AHT, which definitely needs a five-man party.
Some of the quests in this line require you to fly up and speak to Neltharaku in the sky over the Netherwing Fields. There is a bug in the way his interaction is set up, so clicking on the dragon himself just gives you a grey cursor, and nothing happens. The trick is to click in the empty space just underneath the dragon: once you find the right spot, he'll talk to you like any other quest-giver.
An interesting side-note: Once you're Neutral with this faction, you'll find that Netherwing dragons throughout Outland will no longer aggro when you approach. This means that the quests at Singing Ridge in the Blade's Edge Mountains, and Celestial Ridge W in Netherstorm, suddenly become a heck of a lot easier to complete.
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