ok I'm not entirely how true this is or how this can be done but I think if you introduce your body to poisons of a small scale slowly for long periods of time and during a long period of time of injesting different kinds of poisons and antidotes over and over and over again I'm pretty sure though it be torturous it would in fact slowly make your body gain a resistance to poison but you have to get used to the really weak ones first then slowly work into the big time powerful poisons however I'm not sure of this and have no idea if it can be done since a lot of poisons don't have antidotes but I have a slight resistance when it comes to medicine and I've personally never done pills I don't even like taking benedril or Ibuprofen for my allergies or migraines seriously I was born with it even pumped full of sleeping gas or whatever they use to put you out during a surgery I was still semi awake but couldn't really feel anything at 4 years old having surgery on my ears I get sick maybe 2 times a year and it's never something I've had before I always thought it was all the oranges and bananas I ate as a kid I just probably have a natural resistance to things I don't smoke if I ever drink it takes a lot to get me drunk but I only ever really sip some every year not much but in the old days having a poison resistance would probably be pretty important considering many lost their lives to poison