Still, it's interesting to compare the two narratives - Gibbon on Julian the Apostate, Wilson on Julian Comstock - because in the end both are about rulers who acquire imperial office through family relationships and military success, and then try to reverse the evangelical Christian regime established by their predecessors. (I haven't read Gore Vidal's novel Julian, which may be a more direct source than Gibbon for Wilson). There isn't a lot of suspense in either case; we have a pretty good idea how things are going to turn out. The reader's interest in both stories is engaged by the incidental details of the plot and the way in which the story is told.
As to the details, both writers are covering a world we barely recognise. Gibbon has Julian proclaimed Emperor in the great hall of the Roman baths in Paris, which we can still see today. Wilson has the presidential residence located in New York's Central Park. Wilson of course has the harder task here, as he is inventing a setting rather than retrieving it from historical accounts, and there are only three groups of settings described in much detail - the small village where Julian and the narrator grow up, the battlefields of Canada, and New York when Julian arrives as ruler. Wilson's future America has suffered economic and military catastrophe, and seems not to have many non-white people in it (though it does have invading Europeans and persecuted Jews). For Gibbon's past Roman Empire, the big catastrophe is yet to come, though he sees his Julian as the last, lost hope of reversing the Decline and Fall. Each story has a central military set-piece, the army of the West's march from Gaul to the middle Danube and the battle of Goose Bay (in both cases prepared by the central character's earlier military successes) and Wilson has the edge over Gibbon here as he can make up an eyewitness account rather than try to analyse other people's reports.
The most memorable feature of both stories is the way that they are told. The delight of reading Gibbon is that he thinks he is smarter than the reader, and nonchalantly shows it at every stage. Wilson's narrator, Adam Hazzard, is probably not as clever as the reader, and probably not as good a novelist as he thinks he is; luckliy for us, both the woman he falls in love with and his friends Julian and Sam are smarter than he is, and this drives the book's humourous side. As for the central character, though, I found Gibbon's Julian more interesting and convincing than Wilson's. (NB that the author in both cases is sympathetic to the project of rolling back Christianity, though Gibbon disapproves of the details of the attempted restoration of pagan superstition and Wilson's narrator isn't as sure of the virtues of the project in the first place.) The similarity of background and basic plot is there; but Wilson's Julian, once he gains power, starts to become dictatorial while also writing a screenplay about his hero, Darwin; Gibbon's Julian as emperor seems much more consistent in character with his behaviour before gaining power (including his continued literary output).
A final point on languages. Gibbon can nonchalantly throw in extended footnotes in Latin (in fairness, he doesn't do this often) in the expectation that the reader of 1781 will be able to follow the argument without too much difficulty. Wilson has the odd phrase in French (mostly from the narrator's Canadian lover) and most strikingly a letter in Dutch (p. 189) from an enemy soldier, killed in Canada, to his lover; I wonder how many readers will follow it (no translation is given) and get the rather grim joke about the dog on the next page?
Well, that concludes my reading of this year's nominees for the Hugo Award for Best Novel. Without much hesitation, my final ranking is: