But being Toxic seems to be a lifestyle choice. Well if not a choice then a by-product of going a bit insane. Insanity is cured/managed all the time. Some people can even be talked back from "the edge" as it were to rejoin the sane side of humanity.
In fact you give an allusion to an example in your description there, "the Toxic and Dissonant". Now I'm pretty sure we've never seen a Toxic shaman brought back to the light, but I know we have a Dissonance practitioner that has come back over. Puck.
I'm not saying it would be easy, or that I would even want to do it, (I prefer to shoot toxics first and never ask questions) but it Should be possible to "rehabilitate" a Toxic. For casters I would assume that they would have to go thru an initiation ordeal and take a geasa that prohibited them from useing the toxic magic. Then rebuild their magic score from the ground up.
For Dissonance users I assume it would be the same type of deal (mechanically), Or they would have to become Hackers.
I did forget Puck. But just how twisted had he become before he turned around?
Puck was never really a Dissonant. He was an idealist that got suckered in to a cult leader's vision.
Regarding Puck - and
all of Deus' otaku before he left them behind - what Mirikon says is absolutely true. Pax is the first to seek out the Dissonance, and she does so
after she escaped the Arcology, furious that Deus abandoned her and frightened of the fact that she's Fading*. She assembled Ex Pacis from others she found (sometimes through torment) could hear the Dissonance, and the rest is history. So none of Deus' otaku were actually 'toxic otaku'.
However, I believe that becoming Toxic/Dissonant (or, actually, an insect shaman) is more than just 'a lifestyle choice'; it's a complete and utter embrace of that path of power, on every level of the psyche. As Arkangel Winter says, one can't cure that sort of thing, one can only suffer through it.
* - For those who don't know pre-4th edition, Fading was the term applied to the gradual loss of otaku abilities due to the natural neural hardening one experiences as one departs the teens in age. (Fascinating stuff, neural hardening; National Geographic mentioned it in an article about recklessness in teens a number of months ago.) Eventually an otaku would lose all their abilities, becoming 'just' another decker.
Xzylvador's thoughts are, I think, the most cogent ones, however. Bugs, Toxics, Horrors - they make for good 'absolute' events, but if you want a year or three of complications, you need to go with normal, plumb-grump metahumanity. Corporations, organized crime, politics - you might race to prevent the Horrors from crossing over, but that's
likely to be a Big Event that might come around once every year or three. Your every-day work is going to be, well, caused by every-day people. Sure, you saved the world last week, but where is next month's rent coming from? Kung-Fu Lou and his Hong Kong Killers. And the month after that, The Right Hon. Lawrence R. Sims wants you to put pressure on his opponent in the current election. And the month after that ...
You get the idea. In the long run, or at least 'for the purposes of most games', metahumanity is the bread and butter plot generator that's going to make the most difference, and earn you your daily salt. Doesn't have to be Corp or Mob War; can just be 'positioning for advantage'. Shadowruns are about small but vital gains, when it comes down to it ...