I found that Orkus is much more chatty than Dumass and Johnny Awesome, sometimes spamming me with paragraphs at a time. If you let him stick around for long enough, he'll let you in on some of his secrets.
Some things he says:
I wasn't there, but I heard that Sylvanas died in Silverpine and that her precious val'kyr resurrected her at the cost of their own lives. Know anything about it?
<Name>, just between you and me, I never saw the fall of the Lich King. And... well... I've never been to Ulduar. I... well... I am a dungeon explorer. Yes. I prefer exploring dungeons with allies. The pay is excellent and the risk is low.
I liked the worgen better when they were a disorganized mess that you'd run into in small packs. This new Gilnean worgen alliance is much more difficult to deal with.
Hillsbrad has changed. Back in my day Hillsbrad was a place of constant battle. The humans and dwarves of Southshore would constantly attack the Horde at Tarren Mill. There were days when you could look out past the intersection at Darrow Hill and see a thousand people battle. Glory days, <Name> - they'll pass you by.
I have heard tale of the Maelstrom itself opening up, threatening to devour the world. Could you imagine such a thing?
I am sorry that I called you puny, <Name>. When we first met I thought you were just another one of Darthalia's pawns.
Worgen and dwarves working together... What has the world come to?
Varian Wyrnn... I saw him fight once at Dire Maul. He killed five feral scar yetis with his bare hands. Pretty good for a human, no?
I found Kasha in Icecrown. She was injured and dying. I managed to carry her back to the Shadow Vault where the death knights helped nurse her back to health. We are now the best of friends.
This place reeks of evil. It must be purged!
If Ivar Bloodfang is here, where is Darius Crowley?
<Name>, you and I are friends.
Garrosh Hellscream: great warchief or greatest warchief?
If we stop these dwarves and worgen we will be celebrated as great heroes of the Horde!
The longer you afk with him, the more he has to say it seems : I