In my book I spoke at considerable length dealing with the relationship of Apollon and Dionysos, in fact it was one of the more lengthier chapters. But I said very little about Apollon and Zagreus. I came across an interesting little peice of information when reading about Zagreus on theoi.com. Though it comes from Clement of Alexandria, a christian writer, exhorting against the mysteries, it does offer some valuable information. One of the quoted texts mentioned that after the Titanes had killed the infant Zagreus Zeus gave the dismembered limbs of the infant for burial. Now Athena had her part too in that she transported the heart of the babe in a silver box, but it is quite interesting that specifically Apollon had his part specifically in the burial of Zagreus.
“Later on Zeus appeared; perhaps, since he was a god, because he smelt the steam of flesh that was cooking, which your gods admit they ‘receive as their portion.’ He plagues the Titanes with thunder, and entrusts the limbs of Dionysos to his son Apollon for burial. In obedience to Zeus, Apollon carries the mutilated corpse to Parnassos and lays it to rest . . “
In my book I did discuss the role that Apollon has in burial and death, which is in truth a very interesting one, and may mythically stem from his role here with Zagreus. We must recall first that Apollon is highly instrumental in the development of Dionysos. He is directing the road of the younger god. It could be quite easily said that Apollon is probably the first Olympian Dionysos meets in his youthful travels. For first Dionysos travels to Olympos and there meets Apollon at his sanctuary and the Muses in attendance, all of whom greet him. Therefore there is an obviously very early-on established mythic relationship. Apollon also direct Dionysos in those things which he must achieve (rather like the labors of Herakles of which Apollon had informed the hero). Therefore Apollon is directly influencing the rise of Dionysos.
Since Dionysos is the rebirthed Zagreus, the burial of Zagreus by Apollon seems quite significant. Apollon is the god of transition, from birth to childhood, then to adulthood, old age and death, and then about again to birth. He is the orderer of the seasons of life. By burying Zagreus he is taking part quite directly in the role of the transitionary element that brings about the rebirth of Dionysos. More importantly, however, as Zagreus imbues humanity with souls, for it is from the substance of his buried remains that humans are fashioned by Prometheus, Apollon is taking significant part in preparing the substances for the birth of humanity. And he is doing this specifically at Parnassus, a locality of great sacredness where Dionysos and Apollon are both in their parts revered. Humanity is literally be born here at the womb of the earth if we connect these mythic dots, and it is to Parnassus that humanity experiences its rebirth when we consider the flood myth of Deucalion and Pyrrha. The Tempe, which was very sacred in the festivals of Apollon and is well known in the myth of Daphne was created in release these flood waters and the couple landed at Parnassus and consulted the oracle at Delphi in regards to what they should do. So all of these has a very clear connection to each other. Parnassus and Apollon’s relationship with Zagreus is based on a principle of birth rising from the sacrifice of the young god.