I've read some recent theories recently.
Two of the most interesting being that the Emma Frost as we know it is really Jean Grey who adopted Emma Frosts at the moment of her death at the end of Morrison's X-Men run, a kind of amalgamation of the two that explains Emma's need to validate herself as the phoenix. And that 'White Queen' (and possibly the rest of the HC) is an offshoot of this process.
It's unlikely as it flies in the face of both Morrison, Greg Pak's endsong, and reason. But its a cool theory.
Another cool one is that 'Perfection' is really Martha Johannsen or 'No-Girl' who is the Brain in the Bottle from Morrisons run, and is capable of mass psychic hallucination and manipulation. And that 'The Manger' is where Xavier keeps his cloned bodies in case he quickly needs to transfer his consciousness on the moment of his death ( similar to what happens in "X-Men 3") And that Martha wants to get her hands on the Manger so that she can transfer her consciousness into Xaviers Body, but she needs Emma to to this and, obviously, the X-Men gone so that there is no opposition.
Another cool one involved Maddy Pryor, but thats hugely unlikely.
I also read a theory that reckons the Manger is the next step for the Danger Room, and that it manifests threat Psychically rather than Holographically, and somehow its gotten out of hand with Emma's influence.
Anyway, I'd hate for Whedon to finish this with saying that the Hellfire Club is just a huge, collective 'mind****', because its a bit of a cop-out - its kind of like saying "it was alllll a dream", you know, scooby doo style

.
Anyway, I keep remembering some things about the Danger arc, like, how "Danger" knew emma's secret, and how Emma appeared to deliberately 'free' Danger from the constraints of the room... dunno, something there you reckon?
So I'm hoping the existence of the HC is much more than just
psychic constructs.