I am moody. Very moody. I like to think for days at a time, but then I might go off on a tangent where I want to do nothing but be silly, be extroverted, and drink. Then I crawl back into my hole again, sometimes for weeks. So it really depends on what mood I am in as to how I act towards others. In general:
My S.O.: I talk his ears off, regardless of what mood I am in. I like to bug the fu** out of him. Annoy him, pick at him. It gives me a thrill. I like to talk about things I've read that day or something I am analyzing, or work stuff. And he always listens patiently. Luckily, he's an ENTJ so he can handle just about anything I throw at him. He's very patient.
My family: Hardly ever talk to them. My mom I've talked to lately, but my siblings I haven't even seen or spoken to in 7 years or more. I can talk for hours at a time to my mom, and I've always felt semi-comfortable with her, but we have grown apart (mostly because I chose to). We didn't have a healthy relationship and I needed to break free from it.
Friends I know well: Comfortable and confident, but I won't tell them everything. I choose my friends selectively, because certain types are just too much maintenance. I like friends I feel like I can say anything to and they won't be shocked or upset. I prefer friends who understand where I am coming from. Being a female istp can be difficult, because women especially can be offended easily. (I know this sounds like I am stereotyping, but it's just something I learned over the years after many lessons lol - I don't think ALL women are like this, but I pretty much assume it initially until I figure out where I can go and where I can't with them). So sometimes I think I go overboard to let them know I accept them, and I tread lightly around females especially, until I get to know who they are, and then I know which ones won't be upset by me and which will. I need to figure out where their lines are (because sometimes mine are much different from theirs, and I honestly want to respect them). Males I feel like I can be myself with alot more, honestly. The worst thing in the world for me is to get caught up in certain kinds of games people play, and I will try to avoid those at all costs.
Strangers: Pretty much ignore them. Sometimes I will catch their eye and say "hi" and smile. I am friendly and use Fe if I need to speak to a stranger. Other than that, I ignore them.
New People I am Meeting: Tread lightly until I figure them out. I'm usually friendly and use Fe alot until I figure you out. I adjust Fe to fit the situation thereafter. If I don't like you, I'm different from a lot of istp's in that I will still usually treat you warmly. If I'm going to dislike you, the only people who will know it are my closest friends. I keep my enemies close. I prefer to use less Fe, but I do have my lines. If guys become too crude, I get turned off. I like people who respect others, generally, and respect what they want to hear and see.
If it gives me a thrill, I might act in a completely different manner than usual. I am a thrill-seeker, and I'll try just about anything once, even if it is way out of my comfort zone.