(...) also i wish i knew more of the story behind duriel and andariel, they were of the four lesser evils, and belial and azmodan rebelled against the three prime evils casting them out of hell, where is durials and andraials plot in the story?, and are they brother and sister?, i also noticed that andariel's and duriel's names end with the same suffix "iel", kindof puts them together. Just a gathering of my own random thoughts lol. :thumbsup:
Well, according to the trilogy "The Sin War", Mephisto had 2 children, Lucion and Lilith. Lilith had children with an angel, Inarius. Their first children being Bul Kathos, Rathma, and the likes of them. Lilith is also the mother of the Succubi and Andariel. So basically, Mephisto is related to Andariel. I don't remember ever reading something about Duriel's family.
In overall, Azmodan and Belial are the ones with the less story behind them, which we'll probably get with D3. After that there's Duriel, who we've seen but nothing much more. Then there's Andariel, we know a bit about her. Then Baal, which only appeared in Diablo 2 expension, at least that I know of. Mephisto had a bit more story, as we know a bit about his family and he was refered to in some books. Lilith, while not one of the Prime/Lesser Evils, is still strong enough to be considered an important evil, and she left the Burning Hells during the great conflict, which is probably why she's not in the Hierarchy of Greater Evils. And Diablo, well, he made a few little appearance in the books I think, and he was refered to, and he was in both Diablo games.
Maybe assuming one's "true form" is so hard that one needs outside help, like in Diablo's case.
I could see where they need to find a host and be a parasite in this person waiting and slowly corrupting the host till they can come forth. Depending on your power level you'll want either a host you are sure to be able to corrupt and is strong enough to house your enormous power; also you would want to add the hosts powers/resources to your own so you have to be very selective. Some just pick an easy target others research; that sort of stuff.
Does help to have worshipers who can help you in finding the right target and ensure things go well.