Uhm...this is one of those posts where I ramble around for a while thinking things through at you, and probably come to no conclusion and make sense to no one but myself.
But basically, there's this whole massive character type of characters who are always up to something and have something up their sleeve and 50 times more things going on in their heads than anyone knows about, and are often crazy levels of smart. Western stuff tends to cast these characters more as villains, but anime and manga often has them as supporting (or lead) characters, running the gamut from evil villain to the hero's best friend. They also tend to be massively popular in the anime and manga fandom. For me, liking them is all over the place...there are some I adore, and others I want to strangle.
(Obviously, I'm thinking mostly in the anime/manga fan mindset here.)
I've been thinking a lot recently about that: why I love some of the type, and want to strangle others, and I've noticed that, for me at least, they seem to boil down to three types: schemers, tricksters, and plotters/planners.
Schemers:
These are the ones I want to strangle. But instead of the ones I want to strangle, I'll bring up examples of characters I like in spite of the trait, though not as much as I do others. (Because if I talked about ones I dislike, I'd just rant. And despite how it sometimes seems, I don't really like to rant.) Specifically, Shigure in Fruits Basket and Yukimura and Okuni in Samurai Deeper Kyo. (And in Shigure and Yukimura's case, there's another aspect to the character unrelated to the scheming that annoys me, but again, not enough to keep me from liking them.) The schemers seem to, for lack of a better word, flaunt that they go around with some sort of scheme or plot in their heads, or advertise that they aren't telling everything. Shigure and Yukimura are massively popular in their fandoms, as near as I can tell(as far as I know, I'm the only person out there who likes Okuni) and while I'm fond of these specific characters, I often want to tell them to shut up and just say what they mean, quit beating around the bush.
A lot of my annoyance, I think, is the demeanor that tends to come with the characters. The "tee hee, I know something you don't know" and "Oh ho ho! Me? Up to something?" thing. It irritates me. I don't think it's the flippant attitude, as other characters who use similar flippant attitudes to brush things off, such as Fai in Tsubasa, don't remotely annoy me(and, in fact, I often adore them) so much as the flippant attitude combined with the scheming. They also seem to enjoy being up to something, almost as if having something to hold back from or hold over someone, taunting and teasing them and watching them try to figure it out and/or get annoyed with the schemer, is one of life's greatest pleasures for them. The odd thing here is that, when I dislike them, I just want them to GO AWAY, but if I like them, such as Shigure, Yukimura and Okuni, then if they disappear for a book or two(or longer) I get sad and start missing them, then I get excited when they show up again, but then they hang around for a bit and I start getting irritated with them. This, I think, is why, even though Yukimura is the stronger and more interesting character of the two, Okuni works a little bit better for me. Okuni is a relatively minor character after the first handful of books, and she normally doesn't hang around for too long. She tends to either be in the background more, or take off before I stop being happy she showed up again. She also seems to have less of that character type going for her as the series continues, or maybe it just doesn't stand out as much in time.
The strange thing here is this: I often like con artist characters/stories, and those characters are, typically, schemers. I think, though, that perhaps there's more...honesty, maybe, to it. There's also the fact that they tend to get caught in their cons, and have to dif themselves out of the holes they dug themselves into, turning it into a character flaw and downfall as much as it is a character trait. They also often fall a little closer to tricksters. (Example: The "heroes" of Lies of Locke L'amora. They're conartists and tricksters who live for the scam, but they get found out, and the book is essentially about their trying to dig themselves out of the massive hole of epic screwed that they dug for themselves.)
Tricksters:
Tricksters I tend to like. When I think of a trickster, I tend to think of a character who's truly grey area(Xellos in Slayers, Shinkohyo in Hoshin Engi) or seems to be closer to the black side of grey, but really, who knows?(Gin in Bleach.) These characters, even if they do end up mostly helping our heroes, can't really be called "good guys" Schemers, at least in anime and manga, seem to usually be straight good guys or bad guys...even if the characters can't 100% tell which side they're on at first, it tends to be obvious to the audience. Tricksters, however, aren't as obvious about it. They seem as likely to help the good guy as they are to help the bad guy, and when they do help the good guy(or the bad guy) it seems to be more because it suits their purposes than because it's the right thing to do. Xellos often helps Lina, but really only because it suits his own purposes. There are a couple times in season 3(at least where Filia is concerned) where it almost seems he might be helping just to help, but you can't be sure. Shinkohyo is just as likely to help Dakki as he is to help Taikobo, whichever option keeps him entertained. Gin seems to be a villain, but several things he's said make it less clear. My point is that, with these characters, you really do have no idea what's going on in their heads. You have no idea what they'll do, what they'll say, who they'll help, who they'll oppose, etc. They have reasons and goals that have nothing to do with right or wrong, and tend to act in their own interests, which may or may nor coincide who someone else's. They keep you thinking and wondering, which, IMO, is a lot more interesting than a character who acts that way, but whose "side" is obvious.
Planners/Plotters Chess Players:
These are the ones I kinda love, and unfortunately, I don't think "planners/plotters" is really a good name for them, but I couldn't come up with something better. (ETA:
fmanalystsuggested "Chess Players," and I think it works well. Much better than anything I came up with.) These characters also often have something they aren't sharing, but in a different way than the schemers. Yuuko in xxxHolic, for example, has all sorts of things going on inside that head of hers, almost none of which we actually get to hear anything about. Yuuko, however, is bound by rules and laws that prevent her from explaining what's going on, or from interfering, and can't do anything unless she receives a payment of equal value. Sure, she teases Watanuki every chance she gets(who wouldn't?) but it's not that she necesarily likes keeping secrets or hording information, but rather, that she has no choice. More often, though, there's characters like Masamori in Kekkaishi or Teresa and Miria in Claymore. These are cases (and mind you, I could be mistaken about Masamori...it's still omewhat early yet for me with Kekkaishi) where the character has information that they really can't do anything with without it being detrimental to everyone involved.
In the case of the three characters listed above, they all know things about the "good" organization they work for, but can't do anything with it until they know more and can do something about it. They tend to be brilliant, and aren't keeping information back because it's fun, and they aren't flaunting that they know things you don't know, or playing the "guess what I'm thinking/up to" game. When they do play that game, it's because it's part of their master plan, such as Masamori's advertising his position in the organization deliberately to upset people that need to be upset. It's not a scheme and there isn't a personal thrill at annoying or disconcerting or confusing people, but a deliberate goal the behavior helps them achieve. I think it's that it's "necessary" not "fun." Tokine in Kekkaishi also has a lot of potential in this area, but right now she's busy playing den mother to a pair of hotheaded 14-year-olds, and between having the brains and common sense for all three and fighting the Ayakashi, she really just doesn't have a lot of time for long term thinking stuff.
And I really should stop thinking about this, now, as I'm starting to try to categorize every character ever this way. I did, though, pretty much break my brain trying to figure out which of these Captain Jack Sparrow of POTC would be. Part of the problem, of course, is that characterization in that trilogy is all over the place. I think, though, that I'd put him somewhere between trickster and plotter/planner. There's always a hundred or so things going on in that head of his and is more in it for himself with overlapping wants with others and always knows something you don't know, but it's more because it wouldn't be that bright to let people in on what he's thinking, and also because, quite frankly, half of it is spur-of-the-moment brilliance anyway, and let's face it, he just doesn't have time to stop and explain things to the people who can't think as fast as he does. They can catch up with him on their own.
And again, mostly thinking "out loud" and talking to myself in front of everyone. No idea if all that'll make sense to anyone but me.