Draco–the Dragon Clan's bloodline. The Dracos were faithful beings. They never intended to have an affair with a different clan aside from their own.
But Queen Lilith had different ways to seduce anyone. Shirma, the wind dragon, was not an exception.
The queen could have an affair with anyone but as the wife of the Demon King, she could only give birth to his child. Carrying someone else's child would mean death.
At first, Zuriel thought that the reason the Demon Clan was annihilated was that Queen Lilith gave birth to Shirma's child. But when he thought about everything, he realized it was just an excuse.
King Asmodeus was scared of the Dragon Clan's power. He wanted to possess at least one of them to control its power, but he failed.
The last five remaining dragons chose two of his children instead. Azzurth, the fire dragon, chose Athanasia, and Aldra chose Elisia. Endralth, the immortal dragon, chose Amaris who was Asmodeus' granddaughter.