“The mask” isn’t a good description of what they do, but it’s sensationalistic so it’s catched on. What they do is adjust certain parts of themselves. Yes, they’ve got their own personality / emotions, it’s their emotional empathy that’s nearly nonexistent.

You can hear that concept described by Dyshae here, a kid whose been diagnosed with ASPD as well as BPD. https://youtu.be/bdPMUX8_8Ms

Here’s two examples of high functioning psychopaths (brain variant)

James Fallon (Neuroscientist) https://youtu.be/fzqn6Z_Iss0

Andy McNab (Decorated SAS soldier / writer) https://youtu.be/SdOnKB1bn5w

Both Fallon and McNab found out about their disorders while inserting themselves into studies.

Fallon is hyper competitive to the point he doesn’t even let his kids win against him. There’s also a lot of other things he’s said.

Quora’s Athena Walker is an example of someone whose high in sociopathic / psychopathic traits. She did an interview a while back.

Masterclass on Sociopathy / Psychopathy by a licensed professional - https://youtu.be/gpjYtAB9i2w