Usually when someone mentions a poisoned chalice they are referring to something bad. Of course there is a good reason for this, usually poison is bad for whatever it enters into, by definition.
There is always an implied locality and relationship with poison however, and we can only understand its effects within a limited context. Poison has to be something particular, and it has to affect something particular, and then the way the poison and the particular vessel interact has to be particular.
In the most general sense, poisons "disrupt" the locality they occur in. What is to be disrupted depends on the poison and the vessel, which can have various effects. A disrupted body may suffer negative consequences to it, but it may also create new opportunities within itself, as disruption can stop booth good and bad processes, as far as the body is concerned.
Someone may tell you something you really don't want to hear, thus poisoning your psyche, leaving you writhing in a depression. But what if what you were told was some truth about your person, which steadily destroys some bad set of habits upon having it put into words for you? After recovering from such a blow, you may continue on in life changed. Perhaps some unsavory characteristic about yourself was revealed, which has now been broken off, leaving you to continue on in life stronger?
There are plenty of poisons and toxins that are undesirable any way you cut it. Cyanide halts ATP production, and potassium chloride stops the heart. You're not likely to gain much from a food poisoning episode, other than nausea and a desire for it to be over. And toxic relationships, or social phenomena like toxic masculinity tend to destroy the relations around them, oftentimes without building anything positive in their place, though even these things can have other indirect effects that aren't always well-understood.
And yet there are other poisons that have entirely different and unforeseen effects,
Cannabis for example is sometimes referred to as a neurotoxin, though there are numerous debates going on around this classification. Nevertheless if you do smoke too much of it, there is the possibility that it goes bad and you panic.
When you panic, you have to cope. Your ontological security has been temporarily shattered, and you have to go about putting it back together. You can stand to learn quite a bit from an experience like this. I've had a number of panics on various substances and learned a hell of a lot in the process, or else have developed strong spiritual bonds with things like water, incense, various plants or foods, or breathing which helped me through, bonds which proved lasting and functional outside of their generative context.
Various indigenous tribes have their peyote, or ayahuasca, or a number of other substances, and they use them for coming-of-age rituals and spiritual pursuits, which can sometimes resemble the practice of having youth disappear into the forest to go on survival trips. The individual, after having gone through some hellish-but-illuminating trial, now possesses the tempered character required for moving through the world with all of its hardships.
Humans do indeed bond together under extreme duress, sometimes in surprising ways. And this doesn't have to be an argument for war, there are plenty other forms of duress. We see this phenomenon crop up in unlikely places, such as in the surprisingly touching Hands on a Hard Body documentary, in which individuals bond over a seemingly mundane contest of keeping one's hands rested on a pick up truck.
Some of this may echo the Nietzschean "what doesn't kill you makes you stronger" bit. You emerge stronger coming out of the war-like wilderness of the dueling wills. But even the disintegrative, social Darwinist environments can produce unities of their own: we now have the systematized movement of the individual interest, embodied in capital and the market, a toxic entity if there ever was one, which is essentially poisonous to all that surrounds it. So then would a toxin introduced into such an entity neutralize it? What is toxic to the toxic?
Admittedly this is a whole lot of wordplay. But words, when fixed in relation to each other to mirror certain realities, can reveal those realities in limited ways.
