system
Given the following post, respond as if you're commenting on Reddit:
human
[Fallout]What do the East Coast super mutants want?

Why are they loyal to super mutant-kind as a united front against humanity instead of retaining the loyalties they had as humans?  Why do the ones in DC abduct humans and create more of themselves?  Why do they talk about being the 'future'?

All of this is explainable in the west by the influence of The Master, but no such figure seems to exist in the east.  So what does motivate the mutants of the east to act the way they do?
gpt
The east-coast brand FEV seems to be far more volatile towards the minds of its subjects, hence the insane screaming and constant need to decorate with viscera. They aren't really *loyal* to super mutant kind, as much as they're the only things they don't mutilate or mutate.

As for the whole 'future' spiel and their insistence on sustaining the mutant race, it was probably the first information given to them. Again, the old personality and memories just got obliterated, and now they need a purpose, a goal. Seeing as the Vault 87 personnel were connected to Mariposa, it's not hard to assume they had a similar view of the FEV as a potential method of saving humanity.

With that goal in mind, the mutants go out in search of more FEV and people to use it on, because it's the only thing that makes sense to them now.