So it's been speculated that Archer is a homunculus, and that he may be the resurrection of Hughes, since - well - they do resemble one another.
It's also been speculated that the Fuhrer is one as well, though there's been no proof either way, just general shouts of "I think he's one, too!"
It's been more or less stated that the wild child (henceforth referred to as "Moofy" since seventh_shadow has corrupted me) is one; we've even seen the location of his ouroborous seal.
That pretty much means one too many sins wandering around.
- Lust wants Greed out - we know this; she's said so, and Greed's sort of acting on his own anyway. Possibly Archer or Moofy is the 'new Greed'? Because if, at any given time, there are indeed seven of them, then there must have been an old Lust or an old Sloth, before Scar's brother's girl or Tricia were resurrected; those old sins would have been ousted at the creation of these new ones. Greed's the oldest (I believe) so it would stand to reason that he'd have to be 'cycled out'.
- The Fuhrer is not a sin. (Which I'm actually rather inclined to believe - his coloring's off. And maybe that's a silly reason, but all the other sins have been really freaking pale so far.)
- ... The Fuhrer is Envy? <- a little bit cracked, but possible.
- Moofy is not a sin, but an 'independent' homunculus. (Yet the sins seem to want him - to 'induct' him, perhaps? See first theory.)
What's up with Archer?
So the current popular theory is that Archer is a resurrected/homunculus version of Hughes. The only problem I have with this theory is that *someone* must have done the resurrection/created the homunculus. Granted, there are plenty of alchemists out there, some who might even have that knowledge - but we don't know for sure.
What we do know is that Roy was researching human alchemy shortly after the Ishvar massacre, when he decided to become Fuhrer. It's possible he may have his own theory/knowledge, and he certainly would have the motivation/desire to resurrect Hughes.
Excepting, of course, that Roy seems to have all his parts intact. So this is still a mystery ...
More about Roy...
I don't believe for an instant that he's going to "deal with" the Ishvarites as he's been ordered to. He'll go, and he'll take his staff, but I doubt highly that he would stage another massacre. This is the exact thing that he's trying to prevent from happening. If anything, I can only speculate that he'll ... well, honestly, I'm not entirely sure. I suppose I'm just saying that it seems a little strange. I can understand his obedience - this is a man who knows how to play his cards, after all; and I suspect he's gotten very good at putting on masks - but if he actually follows through with his orders ...
Unless, of course, he just doesn't care anymore - which may be part of his reaction to Hughes's death at all.