Enclave finds out he was former RobCo CEO, the Enclave support him ad who knows, Enclave are powerful under a smart man. :biggrin:
If you are referring to the possibility of Mr. House becoming leader of the Enclave, that would certainly not happen. Especially with the Fallout 2 Enclave as Richardson was their leader. Mr. House simply has no interest in rebuilding the United States
as a state to its pre-war condition, which is the Enclave's ultimate goal. So, in other words, House's ideology of "I am the ruler of this new better world" fundamentally clashes with the Enclave's, which is "Rebuild America as it once was".
Mr. House would undoubtedly have been a member of the "Enclave" at some point, which was (I would argue) in the pre-war years a loose alliance of certain higher members of the U.S. Government, corporate leaders, and the military industrial complex. House was the CEO of ROBCO, which owned REPCONN (and REPCONN helped to develop plasma-based weaponry for the Enclave). ROBCO also had military contracts as well (thus the large numbers of American Army Robots) and probably helped to furnish various turrets and other forms of robotic weaponry for the pre-war Enclave.
Now, on to the question of post-war. What would a meeting of the Enclave and Mr. House look like?
First and foremost, I doubt the Enclave would simply attack House or anything like that. I'm sure that most of the Enclave leadership (and possibly many of the soldiers if they've been schooled in pre-war history) would know his name and recognize his connection to the glorious "pre-war past". They would, likely, be a bit hesitant to deal with him simply because he has survived long past his natural lifespan, which may lead the Enclave to conclude he has mutated in some way. If however Mr. House can provide them with some sort of service, then the Enclave would probably readily deal with him. Otherwise they may simply ignore his robotic emissaries.
Mr. House, being the pragmatist he is, would likely strike a deal with the Enclave if he can benefit from it in some way and if he can provide them something in return. Now assuming we are talking about Richardson's Enclave, would Mr. House go along with "the Project?" Highly doubtful, as that path would undoubtedly deprive House of the control he wishes to exert on a rebuilt world. The most he would do is likely strike some sort of weapons deal.
However, if we are looking at a alternate Universe where the Enclave has released the FEV-Curling 13 and wiped the world clean, House would do everything he could in regards to self-preservation.