Dragons, God Beasts, and Void spawn can never have a child with each other. This communion is simply impossible. They can have children with other species, like Elves, Dwarves, and others, but they can never have a child with each other.
Many half-breeds exist across the universe, but never of those of the Prime Species. The reason is simple.
Their genes are too powerful, so the Weave does not allow it. The very source of their existence begins to conflict with one another. Dragons are the embodiment of mana; every part of their existence is tightly woven with it.
They cannot have a child with the embodiment of Aura, the energy that rejects mana. Similarly, they cannot have a child with a void spawn, the embodiment of Aether, the energy of the soul.
The universe contains three kinds of energies.
