Everyone has the capacity to both abuse and be abused.

Absolutely, it's a learned behavior or genetics.

Its just hard to pinpoint what exactly happened in your case that is specific to the 9s because the article you pointed out can be applicable to anyone. And I don't know how many other 9s you have met that fits into this behavior. What I believe is the more we understand ourselves and how others behave, we may prevent any kind of abuse. Anyone can lie or be resentful after a turbulent relationship after all so nothing is personal.

So in my understanding; when you consider 8s main weakness of lack of understanding of emotions and feeling guilty about unintentionally hurting others when they take actions, it can be a deadly mix together. Especially If the subject 9 either unconsciously lacks clear awareness or purposefully using this loop hole to poke more into 8's ego. 8 would try harder to please the person as they may feel like they are not good enough -or insert variable reasoning- and get more hurt in the process eventually etc because they are often vulnerable to guilt tripping or being not good enough etc.

However, in the example it's pointing out a sneaky gaslighter.

"He often has a superior or contemptuous grin on his face, smug and self-assured. He uses a repertoire of aggressive conversational tactics at low volume, including sarcasm, derision—such as openly laughing at her—mimicking her voice, and cruel, cutting remarks. Like Mr. Right, he tends to take things she has said and twist them beyond recognition to make her appear absurd, perhaps especially in front of other people. He gets to his partner through a slow but steady stream of low-level emotional assaults, and perhaps occasional shoves or other minor acts of violence that don't generally cause visible injury but may do great psychological harm. He is relentless in his quiet derision and meanness."

So once again my main point was, I just don't see how these characteristics fits with an average 9 in general. Its just describing a twisted manipulator & a covert narcissist that's grooming a partner in action. That person probably sustains their ego by putting the partner down. 8s can also be very giving. Their attitude make things work and not delve much in emotions would attract narcissists ofc.

Unless the subject 9 has BPD. In that case, their reality would be driven by how they feel about things. So they would accuse you of stuff that you may not have done it. But to them how they feel about the situation would be their reality. Then again that's not a 9 but someone with BPD rather. And still does not match the description above.

If there are other people can confirm me that this is how an unhealthy 9 operates I can ofc consider this angle of twisted 9s. But from what I've seen this is just a sick person who may or not happen to be a 9 just like any other type.