Luther Sloan is the representative of Section 31 in the DS9 series. He was a figure of shadows and deceit, and the problem is knowing what, if anything, we glimpsed of the man was real. We get hints of who he is as a person, and there are times he seems to let the audience in as to who he is behind the mask. However, we cannot trust that any of them are accurate because it all could be a cover or a lie. Was he really interested in being a doctor? Did he mean it when he said that he was glad to know someone like Bashir, who was honorable in ways he was not? Did he really have a side to him that regretted what he did, as demonstrated in his dying mind? Or was that simply a cover to distract them for time? Did he feel bad for neglecting his wife, his children, his family and friends? Did he even have a wife or children? Was his name even Luther Sloan?
He used the name Sloan, so that is his name (in a sense). It might be that some of the things that Bashir and O'Brien saw in Sloan's mind may have been real. He killed himself because he believed that he would not be mentally strong enough to endure the mental probe. To that extent it might be that he could not make up all the details or be as deceptive as he might be normally. Which details are real is anyone's guess.
I always thought that Sloan was completely full of shit, and that while Section 31 indeed exists (thanks to ST:ID, it was nowhere near as powerful or influential as he was making it out to be.
I thought in the dream we did really see the part of him that regrets leaving his family. I'm sure Sloan has built up intellectual justifications for everything he does. "The good pious people like Bashir need bad guys like us to protect them from the evils out there." Something along those lines.
My quandary is was that good guy part of his personality real, or was it just a red herring that was totally constructed and fake to distract them for a while? As the audience, we would tend to think that the normal Sloan portion killed the good guy portion, but it may be that it was normal Sloan's consciousness killing a fake to make Bashir and O'Brien think just that.
I recall he said something after he had Bashir trick the romulans to the effect of saying the dirty cynics like him and the true federation believers complemented one another. The dirty doers like Sloan protect the true believers from an indifferent and hostile universe and the true believers through the glory of tolerance, peace, love and root beer make those hostile and indifferent aliens reasonable and join the federation(eventually).
I would guess that Sloan really thought he was acting in the best interest of the Federation - and not for personal power. He certainly had the wherewithal to leverage himself into more obvious wealth and glory, but opted to remain covert. I don't think it was because he was lazy or unambitious, considering the lengths he went to in order to win the war through his actions against the Founders. He was certainly capable of reason. Not some belligerent conqueror or power-hungry dictator. So taking his motivation at face value here, to win the war and protect the Federation, it might be fair to call him a patriotic criminal. And while he may have maintained his cover to the death - inside his own mind, we saw how he chose to spend his remaining minutes making peace with himself through the roles of his family; I would be willing to believe they were real people. (Unless Sloan himself were a hypnotized sockpuppet for say, the brainwashing Romulans). I might have tried investigating his credentials and background after the fact, to observe how much of his cover story was in fact real. That should be easy enough to confirm for someone actually embedded within the system. Barring any possibility that he was a Q or a Romulan agent, or the like, I'd guess he threw in his hat with the Federation but played by the rules of its enemies. Which raises, actually, very real questions that people in a democracy each have to face. Did he really love his wife? DId he really value a safe and secure Federation? His actions suggest that he did. Otherwise he might have spent his remaining moments trying to persuade Bashir and O'Brien to go rogue and undermine the Federation, not act to protect and preserve it. Section 31 may have a longer, more deeply hidden agenda to subvert the Federation - but in the case of Sloan, this single agent did seem to believe he was acting in the interest of the Federation - and not for some deeper hypothetical consipracy. Otherwise we may have seen some evidence of doubt or regret regarding Section 31 in his last moments; or at the very least, some overarching secret revealed in his vault. No, his greatest concern at that moment was with the Founder genocide - the immediate threat to the Federation. Not some master plan for operating in various war outcomes and contingencies. As an operative, he also seemed to be high enough within the organization to be aware of any such conspiracies. So again, I'd be willing to believe he thought he was acting in the best interest of the Federation, as he averred in his recruitment speeches to Bashir.
If Sloan were a Q he wouldn't have needed the silly secrecy games. And if he were a Romulan or Romulan agent, he would probably have handled the conference a lot differently. I think he's fundamentally what he appears. The family may be made up (a metaphor would be a more polite word) and Sloan might be just one of many cover names, but I think he really is a Section 31 agent who believes he's helping the Federation. And I believe Section 31 is real, at least Admiral Ross thinks it is.