I've revisited the single player, and my guts tell me that the Outcasts actually have a friendly relationship with the Order in Vanilla. A good example is during the mission in which you must escort a convoy of artifacts to Willard, an Outcast group ambushes it. Shortly after defeating the Outcasts, the convoy arrived at Willard, which was under attack by the Rheinland Military, obviously looking for the artifacts.
In my honest opinion, the Outcasts were working for the Order in this case, attempting to capture the artifacts to give them to the Order, and to prevent these artifacts from falling into either the hands of an infected member of the Liberty military/political sphere, or from the Rheinland Military. It wouldn't be the first time the Order would've used another group to do their biddings. The Blood Dragons and the Bundies were heavily tied to them, and even the Liberty Rogues cooperated with the Order. The Lane Hackers also wanted to have a talk with Jun'ko Zane after saving her and Trent in Magellan, which I'm sure is where she first was introduced to the Order, while keeping Trent unknowing about it for now.
