Oh, the Enclave do have a story, just not one that makes them hero's or patriots.
The are the decents of traitors who, instead of trying to help rebuild the US after the war, were content to simply try to hide in the oil rig and the few small mainland bases.
House is more of a hero than the Enclave, and frankly the only reason the Enclave has their nice gear now is because House controlled RobCo before the war and made most of it for them. Heck, House tried to get the pre-War gov to adapt his ABM tech, and they seemed to have ignored him out of arrogance. I mean, if even a 1/4 of the pre-war Us the Enclave claims to represent had the same tech as Vegas, the country would likely have remained a functional entity. Like, when Vegas has a better ABM shield the DC, somethings fucked up. And the Zetans never got into House's shit, either his computers or into Vegas itself.