So why is he wandering about in the courts of Heaven having reasonable discussions with God in Job?

Satan, as a figure in a story, has a lot in common with other characters in stories such as Prometheus and Loki. Prometheus, in Greek myth, is generally seen as a good thing, because of the unreasonable way Zeus was behaving at the time. He was responsible for the creation and education of human beings, and the gift of fire, which was probably inclusive of the fire of the spirit as well as its external manifestation. (I have seen one retelling for children which makes him more Loki or Satan-like, by an author who had previously published illustrated Bible stories, and thought opposing the leader of the gods is always wrong.) Loki had a similar position in Norse mythology, with a similarly badly behaved leader of the gods - look at how Odin describes himself in "The words of the High One". Both came to a bad end, though Prometheus was released. Loki wasn't, because a) Odin was a god of kings and warriors, who couldn't be doing with subversive deities who shout out what the toffs are doing wrong, and b) he was written down by Christians who had already conflated him with Satan.

Satan does not give fire, though the expression "the fruit of the tree" seems analogous with Kipling's Red Flower (musical interlude for Pratchett's Librarian). Jewish teaching regards the 'evil impulse' as positive, having made Adam and Eve adults rather than children. The similarities, especially Satan's presence in heaven in Job, suggest to me that there is a common literary ancestor, expressing something which humans need to hear, and that there is no such being.

Penny