OKAY.
I rp Nagato Yuki. She dots a lot, and she doesn't say much. Even when people directly speak to her or ask her questions.
There is a logic to all of this, and this is it. Behold! Rping notes. XD
[Note: Lots and lots of spoilers!]
Firstly, Nagato's mission and her loyalty to the Data Integrated Thought Entity are foremost. If something serves her interests, she'll do it. If it doesn't, she won't. The only real reason she's so close and talkative to Kyon is that he's close to Suzumiya Haruhi. Anyone else barely registers. (Watch how she treats Tsuruya and Kyon's sister.)
However, she never outright says to someone: "I have no use for you, go away," either. So if someone is persistent in hanging around her, they can maybe learn more about her, or get her to say more than "I see."
Being a data-integrated interface brings with it a lot of perks, like the ability to do pretty much anything. BUT, Yuki has to be sure it will result in something good for her. In the normal Haruhi-universe, Yuki is constantly and accurately calculating what actions everyone around her are taking, and her actions are very subtle. She sits in the club room and reads, and only acts if she detects someone thinks she should. (For example, in the third episode where Kyon begins to think: "She does go to class, right?" immediately after, the bell rings and she gets up to go to class. XD) This translates to: Yuki will dot, stare, and be unintrusive but sorta frustrating to everyone, only really acting if it brings some good to her, in the form of furthering her mission or otherwise gaining her useful data.
Yuki, being an alien, does not get human interaction sometimes. She never greets anyone, she never asks someone generally 'How are you?' and she doesn't respond to such things either.
On some level, Yuki DOES comprehend how human interaction works. For example, when she first meets Haruhi and Kyon, she announces her name is "Nagato Yuki," without even a prompt. And later, when she tells Kyon: "Haruhi and I are not normal human beings." and Kyon is like: "Yeah, really, lolz." Her reply is: "I do not mean in the sense of lacking universally held character traits." Meaning, she KNOWS her actions will be held as weird by normal human society.
But, similar to how a persistent person can get words out of her eventually, Yuki will respond to certain acts or commands:
1. Directly order her to do something. Assuming it's nothing that would conflict with her mission, set her apart, etc, she'll probably do it. Indirect orders, like: "Could you do this?" might also work, or might get a blank stare. "I could do it, but am I doing it?"
2. Ask her any other direct, non-general question. A "how are you?" will get a blank stare. But "what is your name?" Will get "Nagato Yuki." "Can you talk?" will also get blankness, but "Can you produce words/sound?" will get a response. A subtle difference, but one that is there.
3. Try to physically touch/do something to her. Yuki is the master of blocking things, and will block anything thrown at her. If it's a bullet, laser, or something equally powerful, she may block it with her 'repulsion field,' she may find a way to move out of the way, or she may just let it hit her. (Note: If you want to do some sort of action on Yuki and not have her block it, please let me know OOCly. Unless you're Haruhi, her default action is to just block it.)
Nagato Yuki is a being designed to observe. She'll gather small amounts of data (from reading) while maintaining a state of observation over Haruhi, or whoever.
That said, there is no obscenity, irrelevance, or bad data. Only information of various degrees of importance. That is all. Therefore, Yuki will listen to anything and everything, even if it seems like she's not paying attention or projecting a feeling of 'leave me alone,' this is never the case.
I discussed previously why Yuki never projects any emotion, but similarly, Yuki is never really surprised, hurt, angry, or upset. At least, she never expresses it. She can show signs of impatience, but this is a bit different. (Example: her hard stare at Mikuru in the Mysterique Sign episode right before Mikuru introduces Emiri. Also, her order to Kyon that he should "go home and read the book right away," after he misses her message the first day.)
Yuki, depending on the circumstances, is either the most helpful person in the world, or the most frustrating.
When Kyon is attacked, Yuki bursts into the room and grabs the knife with her bare hands, then proceeds to fight in a spectacularly awesome display of power until her opponent is literally dissolved in front of him.
However, when Yuki gets dragged off to play baseball, she does absolutely nothing. She stands there and blinks. She never tries to catch a ball or even move. When it's her turn at bat, she just stands there until she strikes out. She finally ends up winning the game for everyone when she's asked to 'help,' but otherwise, it would seem Yuki was the biggest bump on the log in the SOS Brigade.
Why not? It can't be because the results of the game wouldn't matter, as Itsuki points out that 'closed space' will expand if the SOS Brigade loses (there's the possiblity he was exaggerating/lying, but...). Could it be because she doesn't understand the game? That's a possibility. When Yuki takes control of the computer game in episode 11, she does it after almost a week of practice. That first day, she barely can touch a computer, until she finally goes to knowing almost everything the day of the game. It's possible baseball was the same, only that didn't even give her the incentive to try, because it was a physical sport, not a computer game.
But... suppose Yuki DID understand baseball as a game with rules. This is equally valid I think, because Yuki is anything but lacking information, even about non-data related things. Furthermore, she does finally know how to alter the game in the SOS Brigade's favor once incited to act. So why then, does she ignore the sport until then?
There's really only one reason, and it's the same reason Itsuki and Mikuru fail to do anything:
Though Yuki doesn't lack physical ability when she's, say, fighting Asakura Ryoko, if anyone saw her normally doing things like that, she'd be singled out right away. Thus, she does nothing until a proposal reaches her that makes everyone "weird," by altering the bat. And later the baseball when Kyon throws it, which makes the opponent team gaze in shock at HIS pitching ability.
But this brings up another question: does Yuki really care about being 'found out?' She realizes her projected personality is far from the human norm, and even Kyon picks up Yuki was behind the Mysterique Sign incident eventually. So, does she?
The answer has to be "yes... to a certain extent." If someone observes her doing something that is 'weird' but not 'impossible to happen for a normal human,' she'll do nothing and let anyone think what they will. BUT, if a person observes something truly otherworldly, she will do something about it. For example, when the cat suddenly starts talking, Yuki offers a one sentence explanation: "That was ventriloquism." It may not be 100% plausible, but it is certainly possible, and will look more likely than "the cat just started talking" to any normal viewer.
I... think I'm done for now.
Questions? Comments? ...Existential rants? XD