I forgot about Helios. When was Apollo equated with Helios? --Larry Sanger
In standard mythology, Apollo and Dionysius are not brothers; they are half-brothers, but then so are Apollo and Ares, Apollo and Hermes, Apollo and almost half the gods out there. The idea that the two are complementary is not in the mainstream of mythology, and so probably stems from one of the mystery cults, in which case the source should be attributed, since there are often considerable differences in these (e.g. Dionysius and the Titans). Nothing I have ever seen suggests Dionysius has anything to do with Delphi, so that probably should be attributed as well. Besides, I'm interested to know!