Borderline Personality Disorder aka BPD
This is a stub and needs more work.
We're not as knowledgable about BPD as we are about DID — which is funny because at least 2 of the people in my system seem to have BPD. Let's say we grew up with someone who is BPD, and it wasn't pretty.
Here's how we view the functional/functioning side of BPD in a nutshell, welcoming other opinions:
My worst BPD struggles revolve around how we use our imagination. We can imagine things in a daydream, or we can turn things into a nightmare. Unfortunately these imagined dealings become part of my internalized reality. Add in some unhealthy expectations and it's a recipe for disaster.
BPD centers around how stories we tell ourselves in our imagination becoming our emotional expectations. When something happens, we can tell ourselves a story about the meaning of the event and entirely misinterpret it. Or even better, we can allow our imagination to roam and "project" into the future the things we think may happen and play out scenarios in our mind that are then interpreted as emotionally real. So we can have a fantasy argument with someone and harbor resentment towards them for something we have only experienced through our imagination. When something real happens, we can either frame it in a good way, or frame it in a bad way without checking in with the reality of how we're interpreting it.
Note that BPD isn't about delusions. We don't think the fight really happened. It's our emotional landscape that changed, and we can tell physical reality apart from our imagination and visualizations. It's an emotional delusion, not a mental one.
This wouldn't be problematic enough if it just stopped there, but we can chase negativity or positivity in our fantasies into emotional places that are quite unreal.
What does this really look like, in real life? I have an imaginary fight with my boyfriend. Next time I interact with him, I'm resentful and see everything more negatively — like I've put on Goggles of Negativity and can't see anything in a positive light. This of course has no basis in reality, and he wants to know what's wrong and maybe asks in a way such as "so what crawled up your ass?" — since I'm armed with the Goggles of Negativity, there's really no other way for me to interpret this as an offhand comment, so now I'm offended by it. In my internalized emotional reality, now I've both had a fight with him and he was offensive. So now I'm even more resentful. All he knows is that something's bothering me, and now I'm a ticking time bomb ready to go off. If he does one more thing that I can interpret negatively, since I've already got the Goggles on and that's probably all I can see, I'm going to go off on him.
There are books about BPD that are controversial within the DID community. Let's say if you need to read them, remember you've already gone a step past denial by entertaining the idea that you have BPD or that you're willing to research it if someone else has told you that you have BPD. That's a big deal with any personality disorder!!
So what is the "borderline" in BPD? It's the border between emotional reality and emotional fantasy.
How do I keep it in remission? We keep a stranglehold on the types of fantasies we allow ourselves to have. If we project and feel ourselves getting emotional about it we cut the fantasy off at the pass. "Woah, dudes, that didn't happen, it's not happening, and why are you getting a rise out of it?" We then check our emotions at the door and remind ourselves of what is real. In interactions with others, if we feel ourselves getting offended, we stop and ask for clarifications. "Am I understanding this right?" "Is this what you're saying?" This is of supreme importance when it's relationships with those closest to us.
The danger of BPD — that rise I just mentioned. Adrenaline can be addicting. Thinking you're right and they're wrong, that can puff your ego.
Another big thing to watch out for is being passive-agressive. When you're running around basically doing anything that basically says "Look how badly you made me hurt myself!" you're being passive-agressive. Check that at the door.
A good read through The Gentle Art of Verbal Self-Defense may help you learn what type of baiting and attacking language may be coming out of your own mouth. And if you're dealing with someone who has BPD it's a necessary read, because it gives you actionable language to disarm the attacks.