Did you ever play Final Fantasy 8? Squall Leonheart? Kind of like that.
Usually on the terse side.
I like ISTjs a lot, because I get along with them, and see a lot myself in them, even though I know I'm a lot more intutive and theoretical, thinking about the future and my visions of. They feel, to me, like brothers, or cousins, sort of.
One ISTj I know is my uncle, and he's generally quiet. Pushes his son in sports. Slightly demanding of others around him, but cares for them too. He works as some sort of environmental consultant or something like that, I don't remember.
Very serious persona. Nags with his wife (INFj, likely), a little bit.
His wife is my aunt, and her father is also ISTj (my grandfather).
These two ISTjs are very much a like, though originally I thought my g-father was INTj. The difference is that the ISTj is more focused on the here and now, more practical things. I'm more focused on the here and now in the future (and how to get there). But my grandfather was really, really smart. Totally into "do it yourself". He's married to an ENFj, and the bicker all the time. Check this link out. That is essentially how it is with them. Again, I thought my grandfather was an INTj T subtype because he was really reticent and stuff, but once I learned more about ISTjs it was clear.
(From the link). This was really true in my experience, and should be kept note of when dealing with the ISTj, too. If you are smart and wise around him, he will think more highly of you and give you more approval or leinency, or perhaps be slightly more generous, than if someone is doing stupid things all the time.In general, what this dual pair is distinguished by is a certain 'aristocracy' and isolation from others, a complicated emotional life and fidelity to the sense of duty. One more mutual requirement of these types to each other: be prudent in your actions! For them 'imprudent' means 'not one of us', for they strive to avoid any uncertainty.
If you look like an unstable person, or someone who is not of good character or whatever -- not reliable, or very inconsistent --- then you probably will have a hard time getting close or getting to know the ISTj.
Kind of think of Mr. Darcy a little, too. (Though I wonder about his type. He defintely seems like MBTI INTJ, though --- improving the mind through reading literature, etc etc...). But keep in mind Mr. Darcy. Proud, reserved, watching others character, etc. Think of an ISFj, but colder, and more a T type.
That's all I got right now. Feel free to correct stuffs, though.
PS: I like this description, too http://socioniko.net/en/1.3.rels/index-rels.html