Bethesda made the Brotherhood turn off in a weird way. Instead of a purely technology-focused group, they have turned into the saviors of the wasteland. Of course, they noticed this and made the outcasts, but come on. I'm going off of that the Brotherhood sent people out in airships that crashed in Chicago. No, this will not be a remake of FO: Tactics. You could be a tribal in a small, but thriving tribe. You are a small child when you see the airships crash far away. Your village sends scouts to look at it. They don't return. Time skip to whenever you are an adult. There is a ceremony and a test in your tribe for adulthood. You must prove your worth by traveling the wasteland and bringing something of value to prove your adventures. The problem is, there are few adults left. Almost everybody who has been sent out on the ceremony has not come back ever since the airships crash, and rumors are spreading from scouts about hulking machine-men roaming the hills. Eventually you find Saint Louis, a city that was ravaged by war. Many civilized people have made small towns, and have noticed a faction called the Brotherhood roaming around, harassing people for technology. It seems that they steadily grow in numbers, also, and that the new guys are young adults. Eventually you find out that the BoS has been kidnapping tribals in order to make their numbers bigger. I think that the brotherhood needs this antagonistic turn to show that saving the wasteland's people was not their main purpose.