In my AU, there are multiple different MCs (like, 6 or so) and rather than being pulled to the Devildom in the exchange program without warning, all but one meet the brothers in other ways (more about them later!) The RAD is more like a University or College rather than being a high school with grown adults in it. Most of the brothers are more powerful, such as Leviathan being revered in the human world as a diety (his angwy temper tantrums cause storms much like Zeus) and Lucifer being able to will demons to do his bidding.
The HOL is quite close to lord Diavolo's mansion, and Lucifer is one of the only 3 brothers who still live there. He uses his powers of control over lesser demons to fund Diavolo's goals. He believed that with a sacrifice, Diavolo would be strong enough to pull Lilith's soul into the Devildom as a ghost. Diavolo refused, and their relationship has been tense ever since. Lucifer shies away from the human world, only ever interacting with it when he must for Diavolo. Lucifer is the only one of his brothers that can still fly as well as an angel, although it causes him pain.
Mammon lives in a bachelor pad in the middle of the city in the Devildom. He has caused many mysterious robberies of the rich in the human world. Although Mammon spends his money from his part-time jobs and modeling gigs on whatever he wants, at least half of the funds from his robberies are given back to charities or individuals down on their luck. Mammon can shift metals and control a small amount of electricity. Mammon was revered in the past, but now only very small communities know of him, and only half of them worship him. He misses the praise ):
Leviathan, although he can't use most magic like his brothers, has strong unique powers. Not only can he control Lotan, but also any water in a 2km radius of him (although his power gets weaker the further away the water is.) Leviathan lives underwater near a small town. He is worhsipped strongly by the people of the town, and a festival is held for him once a year. Because he's so reclusive, no other part of the world worships him or believes he's real.