You know, the more research I do on the last years of the Western Roman Empire the more I want to tweak the Roman stories I'm working on. There's another book that I think I have to get about the Barbarians of the time which posits that they weren't all that barbaric and they didn't really cause Rome to fall more than they just happened to be standing nearby when it dropped dead of a massive coronary infarction brought on by years of eating cheeseburgers and watching American Idol. (Or something like that.)
Semi-luckily for me, the adventures of Apollo Valerius Delphinius don't really depend on marauding Visigoths for their story arcs. I'm taking the position that the Empire fell mostly in part to internal weight that just couldn't keep up with a changing reality around them. Of course, in one story I've got a German with a bad attitude as villain but that is offset by an uber-patriot antagonist in the next. The plot for the third story is still a bit too fluid for me to assign bad guy duties yet. Needs more research, I guess.