One recent weekend a few brothers, whom had joined the Andoran Eagle Knights, were out having a good time. Another bunch of brothers, whom had joined the Chelaxian Blackguard, were also out having a good time and both ended up in the same venue... The Dragon's Talon Inn (known for fine women and consorts).
Let's just say that weekend produced a family with strange ties and to which gingerly bound together a family of both neighboring nations whom are at times at odds with each other. "A family of angels and demons" is often how they're described.
In the decades since, their family has made some of the notable noblemen and noblewomen around Avistan. Marcaise Khorece of Cheliax and Margret Delacroix of Andoran made many children and they are the patrons of many more grandchildren. The grandchildren are the ones whom still have the bloodline still today.
One twist fate brought to their families was the fact that both Marcaise and Margret were both gifted with divine backgrounds. It was this fact that brought the nations to such hostility after it was found out. In decades after this was the public sightings of true demons through the Cheliax nation, and angelic avatars in the Andoran nation. It was thought that the gods were just fed up and sent their avatars to the material plane.
To what ends has yet to be determined as this is the current time when the party "comes of heroic age".
Rumor has it that some of the ancient deities (the old ones) have taken notice to this as it was a common practice "back in their day". One such deity's minions and worshippers have whispered that he has awoken from his deep slumber and wants to return to power. The only place this such deity was rumored to have access to the material world is kept hidden in many ancient texts. It is within these texts the party is to be geased by both nations as both are being torn asunder in the charismatic sense of the word. This act of joining of such opposites disgusts many religious leaders on both sides and it is they whom hire out the party...
Cheliaxian representative, "I only wish that the text be returned to us so that it may be treasured and kept secreted away from treasure hunting zealots".
< ... in secret, they confide with any evil aligned players that they wish to curse both families into service... fresh demons without a true master... and the texts will reveal the entrance to one of the found fathers of old >
The demons turned the families into goats whom are very old but whom are immune to mortal harm.