Well, that's understandable... in some cases, emotions probably shouldn't be the issue. Sometimes people make them the issue when they shouldn't be (like in a theoretical discussion when we're trying to understand something... that can actually drive me up the wall.), but sometimes they bring them up because they are actually the crux of the whole thing. It's important to know/learn the difference, though.
That's right. Emotions sometimes are the focus of the discussion and can't be shoved off. But when they're dragged into what the INTP thinks is an impersonal "ideas" discussion...? Ouch.
Hmm... but sometimes INTP's (perhaps unconsciously) do this to other people even though they don't like it themselves. I don't really think anyone likes to be controlled.
We do consciously try to avoid controlling others. I know I feel guilty when I do, though.
Like the example above, about the family "leaving the house / going for a walk" when the INTP is in a bad mood? I would feel guilty over that. Because I have no desire to impose, I just want to be alone and have my space... but now all of these people changed their plans to accommodate me... and are seemingly annoyed with me because they feel like I was controlling them (!).
Well, I never asked for them to go, nor even wanted them to; I was controlling myself, not them, by removing myself, and I would be SO frustrated because they were attributing control/imposition to me that I was actively avoiding out of respect for them and being a responsible non-imposing adult.
That is why I know I tend to withdraw *completely*. So that no one feels the need to read into things, trying to accommodate me without my request, and then feels resentment towards me or misunderstands. It is easier just to go FAR away from everyone sometimes, to avoid the misunderstanding and not have to worry about managing someone ELSE's feelings when I'm already in a bad state with my own...
Of course, some of the time all I have to do is keep trying to understand the situation, and often in explaining it to me, they solve it. Sometimes a "sounding board," or an outside perspective is all they need. Do you agree with that?
Uh huh. Sometimes solutions are good (if offered as suggestions -- "What about...?" ...and you don't become exasperated when I explain why everyone one of your suggestions has some small hole in it that renders it unsuitable...
Sorry, I know I and other INTPs can seem annoying as all-get-out when we do that.)
I try not to be controlling, but sometimes I get that way out of irritation or fear, and sometimes I just come across that way because I can seem more decisive when I present my perspective when I'm actually still willing to listen to another perspective that would change my mind about it.
That makes sense. I did figure that out in general with people... but it took me a long time. I think it helps if the person helping reasserts explicitly that they know they sound decisive but they are very open to suggestions; it gives permission to challenge without fear of personal conflict and an emotional mess.
Given I'm also an NT, I doubt I focus on feeling that much, so I think I'd be a dreadful failure at "oh dear... how do you feel about it..".
Ask her what she "thinks" about other people's feeling-based reactions/behavior, and you'll get a very good idea of how she feels... listen to tone, word choice, body language, and whatever else, along with content.
I kind of drag everyone out of the house when she's in one of those moods, or suggest a walk on the beach, basically, some quiet activity. But it creates a fair bit of tension in the house, which stresses the family somewhat. They see it as her being selfish/venting on them, but I know it is not that.
Exactly. In fact her behavior is the opposite, most likely. She is withdrawing to protect them, most likely, and so their accusations would be even more upsetting.
I don't think I misunderstand her as much as others do (hey, ENTPs are not that bad.. really... we're just as misunderstood...)
I love ENTPs. Once we get that Ne cycle going, it's hard to stop and everyone usually is convulsing with laughter.
you mention that "I don't believe emotions are fluff now, but it took a long time to get to the stage where I treated them as part of myself. " - how'd you get to that stage / what was the biggest help to you that in a sense, allowed you to be gentler on yourself vs always wielding a sword at yourself.
ugh, I have no idea what to tell you. I'm nearing 40 now, and most of it was simply the life process. I experienced what worked and what did not, and what allowed for me to remain sane and what did not, and I developed many different types of relationships as an adult that I did not have as a teen, and all of that helped soften me and forgive myself. But it took a long time. So she will get there, it just might take some time.
You should be good for her. The more you get her to Ne (your strength!), the more she can get outside of her head and the Ti self-critical process. Help her to have fun, loosen up, laugh, explore... and not necessarily judge everything right away. Ne is probably her key to freedom -- give her a reason to dream and to hope and to live. Ti just tends to hack you down at the knees.
When I was a teen, the one thing that really helped (because I had no one to talk to about things) was going into a dark room and playing the piano. It was partly a feelings exercise (I did not have to put my feelings into words, the music represented my feelings) and partly an imagination/intuition exercise (because I was listening to what was coming out, then coaxing out more and/or responding to what I was hearing). It was really the creative introspection without any judgment being passed; the music just WAS, like my feelings just WERE... and the criticism would shut down during that time.
Any act of true in-the-moment creativity your sister could indulge in will free her momentarily from the criticism. Note: She is not allowed to EDIT her art as she does it; she simply must be engaged and creating.
Or if I leave her alone, she'd figure it out? My fear is that she'd just reject people, and herself completely if I leave her too much alone.
you do not have an easy job, I know. I think it's wonderful you want so much to be there for her. She is lucky to have someone so concerned about her and willing to engage.
It is a fineline between pushing her and inviting her. The latter is good -- invite her to come out of her head when you can, and have a good time with your own life. It's like the stray kitten and the saucer of milk. You need to put the milk down within reach, then enjoy yourself and give her space to sneak up and drink. If you pressure her, she might hang back. It's got to be her choice... but you can create a safe and enticing environment. Does that help?
Because I think that deep down inside, an INTP craves acceptance and forgiveness more than anything else? And that's not something you get by being alone, is it? I could be wrong.. I'm a flighty ENTP
Oh, on one level she's probably jealous of you... even while being annoyed at how scattered you might seem sometimes. Because you're enjoying your life, and she's feeling alone and incapable of ever being you.
Acceptance/Forgiveness might not be something she can articulate as a need until more time has passed. But I think it is good for you to keep it in mind, to help you remain accessible and open to her.
I hope that helped. I know it's all abstracted.
Maybe Varelse or the other younger INTPs can help? They are more in her situation and might be able to give practical advice...?
(Honestly, don't actively TRY to push/pull us out of our shell. It's annoying most of the time...) Give liberal space and alone time. 
