I think Malacath's quest is related to the Orc strongholds, I think it starts after seeing some orcs fight off a giant around one of the strongholds and talking to the chief after that.
Besides the Malacath quest which has been mentioned, there's a delivery quest from the Reach's stronghold. I haven't found any stronghold quests besides that.
Yea i have been there and they said talk to the chief if you need anything but nothing leads to a quest
I activated the quest by talking to the wise-woman iirc.
I did receive a quest at a stronghold a few days ago. I don't remember the location name, but the chief gave it to me and said that if I completed it (I had to get some gloves from a nearby dungeon), then I would be considered orc-kin by all of the orc tribes, and I could come and go to strongholds freely as well as trade with the orcs. This was on a non-orc character. So there is at least one quest out there that I am aware of.
So, I did the Largashbur quest to retrieve the gloves. However, as soon as I entered the tent to speak to the chief the occupants immediately attacked me. My character is not an Orc, and I didn't initiate the attack. Could this be a glitch related to the Malacath quests (which I haven't started yet), or is it just an organized ambush by the camp.