The Jester is a two part series comprising The Game (a novella, the print version found in the collection Slipping Through) and Pool of Players. It's a dark sci-fi fantasy time travel story set in post-apocalytic and dystopian time parallels.
David Sinclair has been pushed out of his own time, or slipped through like many of his countrymen before him. To return he has to catch The Jester, but that's not a simple task when he keeps slipping through into a different time every few days. In the first book he finds help and in the second, he endeavours to unearth the evil man behind it all, The Jester, and expose him. But David finds more than he bargains for and realises that time is not quite as it seems.