GerIta AU with naiad!Italy and human!Germany. Contains smut.
GerIta. I once read a story (I think by George DeValier) where there's a throwaway joke about Italy trying to learn how to say "fuck me harder you magnificent filthy German sex pig" in German. This tells you everything you need to know.
Historical Germanbros fic. Prussia takes the Confederation of the Rhine under his wing, and the kid should probably get an actual name.