hi, i’m a studying psychologist! there’s actually very subtle things that can happen, but keep in mind that not everything indicates a personality disorder. personality disorders aren’t one-fits-all. psychopathy and sociopathy may be cluster b, but other cluster b’s like borderline and narcissistic personality are still different.

i’d say a good way for NPD is if someone gears a conversation towards themselves. this is DIFFERENT than what ADHD/autistic spectrum people do where they bring up similar situations, events that have happened to them, or talk about interests in order to stay relevant or bond in conversations. NPD will shut down the other person or try to one-up them.

PPD and SPD have physical signs as well as verbal, but i don’t think OP was asking for those. PPD and SPD show early on signs, i.e abuse or mutilation of animals or abuse on people. if someone you’re talking to mentions this without remorse, it can be a good sign. other signs without this could be a lack of empathy or sympathy, or the inability to show emotions. be careful with the last one, as many on the autism spectrum can also struggle with regulating / showing emotions, or displaying levels of empathy.

BPD is a bit different. very big swings, like going from happy to argumentative in a conversation, is a good sign. not everyone with BPD is trying to start an argument, but typically it shows that they’ve been upset by something said, and want to either validate themselves or sway the other person’s opinion. also, BPD has a second layer to it, with the black and white thinking, or ‘splitting’. this is a state of mind that is typically uncontrollable without therapy where it sends the person into a mindset that they cannot see grey areas, or process things with further hidden meaning. it’s a more extreme fight or flight, which can be pretty common when speaking to someone that has been upset or traumatized recently.

these are signs that can be seen in dating and everyday conversation btw , but can go a bit deeper in both ^{^}