Still, no. The mash-up leaves out alot of details, ones that really don't work together, not to shoot it down. Mages for example are not going to be easy to explain, especially since the Earl would want them gone so as to not boost the Exorcist's standing army with mages. Not only that, but the whole Nobility system comes into question. Plus, there is the fact that the Earl operates on a Global scale, and Tristan and the other Countries are like a singular large Continent. Ultimately, the worlds do not mash up well, not with massive screwing of one world or the other. As for Danny Phantom and Devil May Cry, you would be surprised. It takes place in a similar, if isolated, part of the Modern World. The setting for many missions and fights were large cities and country villages. It is earth, albeit slightly different. If we treat the DMC as a sort of "Hidden Aspect" of the world, it suddenly becomes a perfect fit. Also, I was hoping someone would jump on that bit of Expo there and try to take off with a idea, but sigh.