“At the Cross-Time Jaunter’s Ball” by Alexander Jablokov has the protagonist, the alternative history critic Jacob Landstatter, thrown about through various worlds with minor or major changes to history (mostly very America-centric) while he deals with the issues of his marriage, the artists he critiques and the Lords who base their purchase of worlds sometimes on his critiques. As a nice gem, a world that is undoubtedly ours turns up as one of the alternations in this game of reality/realities.