On Discworld, the idea of karma figures quite significantly in many aspects from everyday life to the afterlife to the next life. Karma acts as a sort of balancing force for good or bad, planning out ironical fates for those who wrong or do right (but mostly those who do wrong).
In the case of Mr. Pin, who became acutely aware of his own mortality and sins after being exposed to large quantities of dark light, he worried that he was doomed to fry, but so long as he kept his potato, would be safe from such a fate. He would die, but was eventually reincarnated in the shape of a most unlucky potato in the garden of Josia Wintler. On the advice of one William de Worde, he was made into chips.
It has been long known to members of the Ratcatchers' Guild that the Death of Rats would under certain conditions, appear to any deceased ratcatcher to reward them for doing his work. They are half right, as he would appear to collect their souls. However what happens afterwards is that they are shown to a revolving door that reads on the top 'REINCARNATE AS RAT UNTIL FURTHER NOTICE'.
Rincewind presents an interesting case. Although leading a relatively blameless life, he is subjected to every possible misfortune that comes his way. There are two theories to this, presented by himself:
- The first theory is that somewhere out there, someone is leading a very fortunate life, and every possible good thing that can happen happens to him instead. To balance it out, Rincewind leads a very unfortunate life, and suffers every possible bad thing that can happen. If this is so, Rincewind would like to have a chat with him, presumably while carrying a blunt instrument.
- The second theory is that he suffers from pre-emptive karma: any potentially good act that can happen to Rincewind is immediately counterbalanced in a way that over time, only bad things happen to him, as they keep happening before anything good can.
Of course, many of his misfortunes could simply be due to being a pawn of The Lady, which while it helps ensure his survival in highly improbable cases, subjects him to trials and torments few would ever experience.