Okay, no preamble this time, I will just jump right into saying opinions about fictional Star Trek dudes.
Deanna Troi: Ship Counselor
This is a character that never should have existed. The original series got its T&A in by regularly introducing sexy aliens. TNG is too high-minded for that, by and large, but its solution sort of undermines that apparent high-mindedness: they just brought the hotness on for a full-time job. You could do a lot worse than Marina Sirtis for eye candy -- she's curvaceous and relatively dignified, with ludicrously thick, shiny hair -- but while TNG pats itself on the back for giving its female officers proper pants, it inexplicably provides Troi with her own wacky uniform: purple, with cleavage. Wikipedia tells us Gene Roddenberry meant for her to have four breasts until his wife told him that was retarded. (Not sure what's supposed to be sexy about extra breasts, anyway.) They give her a proper uniform eventually; I'm not there yet. But there's no fixing her character.
The thing about Troi is that she's half-betazed, which means she's an empath. In other words, she can tell how people are feeling with brain powers. If the show ever confronted genuinely weird aliens this might come in handy, but when it does she's generally useless (their emotions are illegible to her, which actually makes a lot more sense) and for the most part the aliens are just guys with slightly weird heads. You don't need telepathy to know what a Klingon is feeling: he's mad. A Ferengi is feeling devious. A Cardassian is probably up to no good. She never tells you anything you don't know, and often she knows less than you do (because drama requires villains, but also requires that she occasionally fail to recognize them). Her power is useless. Also, John Campbell made a good comic about it.
As a counselor, she's abysmal. She often comes to characters who clearly want nothing to do with her and harangues them with banal insights until they give in and pretend to have an epiphany so she'll leave them alone. That is not what counselors should do. Basically every minute she spends on the screen is at least a little painful.
Chief O'Brien: Transporter Dude
He is a pretty good character played by an appealing actor, one of those side characters who gets more and more attention because it turns out he is cool and fun to write for. He was better in DS9. But check out that giant Irish head. That's incredible. So huge.
Lt. Cmmdr. Data: Awesome Robot Dude
Data is clearly the best character on the show, and also, he could beat up Worf. Basically without him I doubt I would really watch the show; Picard is awesome, but he's only awesome. As an android, Data's limitations give him a vulnerability that I really appreciate, and Brent Spiner's performance of the role has always been really charming.
One thing the best Data episodes share is a commitment to his limitations. Data can be brutally honest, as in an episode where he tells a mother who has just killed the Crystalline Entity that her dead son, whom she meant to avenge, would be disappointed with her. In the episode where he gets, half by accident, a girlfriend, he is always explicit with her and everyone else that he can never love her, that this is literally impossible. When she finally understands what this means and leaves him, he is totally unaffected; he pets his cat, Spot, absently, alone in his room. He does not appear sad. Even the way he pets his cat is a bit cold: a repetitive, mechanical motion that does not, as far as I can tell, bring pleasure to the cat, or even care very much if there is such pleasure. Petting for petting's sake.
And yet watching the show now, after several years of education in literary analysis, I can't help but be suspicious of the idea that Data has no emotions. As a kid I recognized that the actor would not be able to portray such a character, that the writers could not manage one, and that the show was not wholly invested in his emotionlessness: the characters occasionally prod Data, bemused, suggesting that he is behaving more like a human than he realizes. He generally shrugs them off. There are cutesy suggestions they are right. But the more I think about it, the more I suspect he's feeling things from the beginning, as much as anybody does; his emotions may be strange, but they're as real as yours or mine. For one thing, he regularly simulates emotions in order to communicate effectively with others. When he needs someone to follow an order, he behaves as if he is irritated and then angry. When he needs to be calm in order to get the reaction he wants, he is calm. At this point in my life I am skeptical of the supposed difference between behaving as if angry and actually being angry. And, most importantly, Data clearly experiences desire. He wants very badly to understand humanity. He wants to become human. He wants to be a good friend and to help people. He wants to be a good Starfleet officer. You can say he's been programmed to want these things if you like, though I don't see much evidence for that, but you can't say he doesn't want them.
And if he wants, then what happens when he doesn't get what he wants? What happens when he is alone, if he would rather have a friend? What happens when he misunderstands humanity, if he would rather understand them? What happens when he succeeds? It seems to me that whatever happens to him defines the concepts of disappointment, frustration, satisfaction, elation: that these emotions, whatever our particular experiences of them, are the necessary results of desire. If we want, then all the rest follows. And Data clearly wants.
This casts an interesting light on his interactions with other characters. Though they behave as if excited when Data seems to evince human emotions, by telling him he is perhaps becoming more human they continually reinforce the idea that presently he is not. Star Trek is chauvinistic about humanity, with Captain Picard and others continually lecturing other species about what makes human beings so special. Generally the other aliens seem to accede to the idea that humans are different, unpredictable, special, unique, though there are no appreciable differences in evidence. By telling Data that he is not like themselves, the human characters get to feel as if they are not machines, when in fact they seem to be more similar to Data than not. By telling him occasionally that he is experiencing humanity, they further construct themselves as special, and the gulf between living being and machine as wider than it really is.
This theory seems to be endorsed, though accidentally, by Data's emotion chip. The chip is designed by his "father," Dr. Noonian Sung, who perfected it just before his death at the hands of Lore, Data's brother, who already had emotions of his own. The chip is tiny, it is simple, it is easily installed. When Data puts it in he has emotions, just like that. It seems implausible that such a thing should be the difference, that Sung could make a machine capable of movement through 4-dimensional space, capable of passing any Turing test, capable of handling complex language, without managing to create a chip that would tell Data, "You feel sad." It's as if all the chip does is give Data permission to feel what he always felt, to be what he always was.