“There is a lot of historical friction between the redguards and the bretons,” explains game director Matt Firor. “There have been a lot of little wars between them, and there has been as much internal fighting in High Rock as there has been with external provinces, but it’s a much more settled area and a little more peaceful. The Bretons have given the orcs their own homeland within their territory, and all three races like and respect each other. This faction is a lot more democratic than the others.”
http://www.gameinformer.com/games/the_elder_scrolls_online/b/pc/archive/2012/05/14/elder-scrolls-online-faction-profile-daggerfall-covenant.aspx
I find it hard that all three races like each other, but let's work with it.
The redguards and bretons working together isn't too hard to see. They've teamed up numerous times to besiege orsinium. However, what might have caused the bretons to extend an olive branch towards the orcs? More importantly, why would the followers of Malacath accept the offer?
For starters, let's work with the idea of the orsimer teaming up with anybody. It seems unlikely that they ever would, simply because of Malacath's disliking of physical weakness. "Allies make you weak! They fill in for your own weakness!" etc. So why might the orcs make any alliance? I figure that the orcs see it as an opportunity to demonstrate their strengths to their allies, which leads me to my next point.
Why would the orcs ever be in an alliance with the redguards and bretons? My thinking goes: How else would you demonstrate your ferocity and strength to your two oldest enemies and leave survivors to tell the tale?
Something else is bothering me, though. How did the man (or woman) who submitted the idea of making an alliance with the orcs not get ridiculed out of the court? Besides an extra fighting force, excellent smithing and one less foe to worry about, what else do the bretons stand to gain from giving lands to the orcs? The following is pure speculation (i.e. much more speculative than the rest of this thread), but I figure that the bretons will try to levy taxes on the orcs at some point.