Let's start with your sister. I don't see her as a rebel, your term, or a nonconformist, which is the better term for this discussion. She may be either of those but I don't have enough data. What I see from this discussion is that she is spoiled and learned at a young age that she could get her way by manipulating with tears and stubborness, as you said. Toward the end you said she accepts responsibility but throughout you said she never admits guilt, so, I don't see her accepting responsibility.

You say you are a conformist. I'm not sure that's true. You moved to Germany and have an excellent career in probably a male dominated field. Is that conforming? What you see in yourself as conforming is more your people pleasing nature and yes, you could probably use some more boundaries. Empaths in particular really need boundaries so that other people don't suck their energy out of them.

Here is how I see nonconformist vs conformist, in the words of Hermann Hesse: “We who bore the mark might well be considered by the rest of the world as strange, even as insane and dangerous. We had awoken, or were awakening, and we were striving for an ever perfect state of wakefulness, whereas the ambition and quest for happiness of the others consisted of linking their opinions, ideals, and duties, their life and happiness, ever more closely with those of the herd. They, too, strove; they, too showed signs of strength and greatness. But as we saw it, whereas we marked men represented Nature's determination to create something new, individual, and forward-looking, the others lived in the determination to stay the same. For them mankind--which they loved as much as we did--was a fully formed entity that had to be preserved and protected. For us mankind was a distant future toward which we were all journeying, whose aspect no one knew, whose laws weren't written down anywhere.”

That could also describe a rebel with a cause. Your sister's only cause that I see from your story is herself. At least those are the only examples you gave. You said she won't stand for any dominance or oppression. Did you mean of herself or that she stands up for others? The latter would make her a rebel with a cause.

The mark Hesse talks about is the mark of Cain, not as discussed in the Bible--his own interpretation. https://medium.com/know-thyself-heal-thyself/my-mark-of-cain-de5db04c5249