I know who the fifth cylon is

Tom Zarek scores higher than Gaeta as the potential "fifth cylon" for several reasons, both within and beyond the show’s storyline.

The actor who plays Zarek, Richard Hatch, is a relatively "big deal" within the production realm of the show, having played Apollo in the original series, as well as working on a film adaptation called ‘Battlestar Galactica: The Second Coming’ and a second continuity comic called ‘Battlestar Galactica: Zarek 1′ about the character’s early life as some kind of pirate. This isn’t definitive, but it does increase the liklihood that he’ll continue to be featured in an important way in future episodes.

Not only that, but it would be consistent with the use of an actor who played a former protagonist, newly cast as a "shady guy" like Zarek if he turns out to be a Cylon.

Within the story itself, there are 4 characteristics that all of the final five share that is absolute, something that Gaeta doesn’t display: they all share the same uncanny knack for "genius" in order to a.) survive, b.) better serve their own interests, c.) gravite to characters of influence within the fleet (and perpetually charm, seduce, bargain-with, or otherwise ingratiate themselves on those individuals — in other words, "to ensure their investments"), and finally d.) to espouse and remain fixated on collectivist philosophies and political positions (i.e., Tyrol and his labor agitating before and during new Caprica, Anders collecting and organizing resistance on both Capricas, etc).

In the episode ‘Colonial Day’ Zarek talks to the press about his collectivist political ideologies. All Cylons espouse collectivist sentiments and ideologies, even to the point of absurdity or non-sequitor, managing to always end up in leadership/valued positions within any group they pass through.

Another major characteristic is one of centrality to the plot: compared to Gaeta, what has Zarek done to help move the plot along at key points, and never fall into the backdrop of events (the way Gaeta has done since the beginning)? Who is more ubiquitous, Gaeta or Zarek? Who is more pwerful, and therefore capable of being a useful tool for creating the "cliffhanger" effect with his position in major events, Gaeta or Zarek?

Tom Zarek is ubiquitous and has never diminished from his role as a central character. Despite fewer appearances throughout the series, he sometimes seems to out-perform even Baltar in this capacity for self-interested behavior and being in critical positions at major plot turns.

This obsession with self-preservation would also explain why Zarek didn’t just wander around until he found the other "final five", who all shared a common history as allies, and could be plausibly seen together without raising suspicion. Zarek would naturally keep a low-profile if he realized he was a Cylon, since hanging out with people who he has never been officially allied with would arouse suspicion, and he would realize this being as shrewd and secretive as he’s always been.

Zarek is the ultimate machiavellian, has connections to all players within the fleet, even the criminal underground, while staying powerful in mainstream politics no matter how the circumstances change. His only true ally is himself, and his self-interest regularly eclipses his temporary associations because he never loses sight of his strategic position. All of the current "four" also make similar pragmatic alliances, like Zarek, but unlike the four that are known, Zarek has never been considered a friend of the Galactica crew like the other four, and has always been more of a "dark horse".

For this reason I can see him making an ideal "alpha Cylon" within the final five, or fulfilling countless other roles once his identity is revealed. Nominating Lee to the chorum might also turn out to be part of a ploy to gain legitimate access to the Galactica, so he can pursue his urges to meet up and contact the others.

Zarek has a history of single-handedly rallying almost anyone to whatever cause he needs to weave around himself, whether its prisoners on a transport ship, members of the hoi polloi in the chorum, officers on the Pegasus, or gangsters in the black market — just like all other Cylons, he’s charismatic in one way or another, and can talk himself into positions of trust and authority.

Zarek appears in a ‘Deus ex machina’ fashion when least expected: he went to Cobol, and was kept outside with Tyrol when the star-map to earth was seen in the tomb of Athena; he helped free and harbor Roslyn; he leaves bread-crumbs for Lee Adama to the prometheus gangsters, and yet, is seen associating with them after claiming not to have connections there; he helped Baltar during the election and ditches him once they’re on New Caprica; he was sentenced to death for resisting the Cylons, and wasn’t a major part of the resistance, but managed to keep tabs on all its leaders enough to organize them into an execution squad once they were off the planet; he starts the execution squads but ditches the burden on Rosyln at a key point and simultaneously buys his way into her office as VP; he was a political activist/terrorist fighting for collectivist ideologies on Saggitaron before the Cylon wars, and for all purposes, has continued to build and manage his own kind of shadow government within the fleet since he was liberated from the prison ship in the early days of the show.

Zarek has remained a constant threat and potential ally at the same time, a powerful and dynamic character on the show. Gaeta is only ever a supporting feature of things, adding texture but rarely substance, unlike the other characters recently revealed to be cylons. Gaeta, if he turned out to be a Cylon, would be quite a surprise given that he would be the ONLY Cylon lacking in "strong-willed" personality traits; he is the ultimate "follower" out of all the characters on the show, and perhaps even one of the most naive among the crew — definitely not typical Cylon qualities.

My biggest question to the "Gaeta for number five" crowd is this: of what value is Gaeta to the plot up to this point, and from this point on? If the VP of the fleet turned out to be a Cylon, especially one as ominous and unpredictable as Zarek, it would create suspense and doubt about the future of the fleet. The same can’t be said about Gaeta, who could live or die without affecting the fate of anyone.

Sounds harsh, but someone tell me I’m wrong on this last point; I just don’t see Gaeta being a valuable tool to the writers or the story progression as a Cylon, especially after all this suspense about the last one’s identity — I can just hear the moans of "WTF?" if it turns out to be him — where’s the "thrill" if Gaeta is a Cylon?