Interesting bit revealed during Patch 5.1 events involving the Black Harvest warlocks:
The Doomguard, the 'Ered'ruin,' were apparently a servitor race of the Titans, presumably created by them like every other servitor race they've used in the past. How many other demons were failed, outcast, or corrupted Titan races, I wonder? How much of Sargeras' job fighting demons was really him cleaning up the messes of his fellows?# Your kind far predates Sargeras's betrayal. What WERE you?
# This knowledge is useless... what are you trying to achieve, Kanrethad?
# STAY OUT OF THIS! The demon will answer, NOW!
# What an odd demand. Not even my own kind care about our origins. Why should you?
# If you do not care then there is no harm telling me.
# ... before Sargeras freed us, we were the Titan's hounds. Forever enslaved to police the use of arcane.
Lots of other interesting tidbits on the front page right now.