Author's Note: This is short -- deal with it,. It's only the history behind the story so no one's confused. Or... so you're less confused. The next one's longer.
Prologue – history
Within four terms as King of Demon World, Enki was getting older and less willing to take the throne again each time he fought for it.
By the sixth Koku had taken over for him and ruled by his laws. She remained in power for another two terms.
Nearly thirty years had gone by, marked by prosperity and peace. But Koku was getting on in years and couldn't hold the throne forever.
That was where Saicho came in. The next king of Demon World.
Siacho lifted all laws pertaining to the consumption of humans. He allowed his demon brethren to roam freely in the Human World.
Thus did the humans become aware of the existence of demons. Panic struck the lands and anarchy reigned all over the world. The demons pillaged and burned the cities, looting, raping, and eating to their hearts' content.
No one was safe.
By the time Spirit World became aware of this problem and sent a team of the Special Defence officers to reinstate the barrier, Saicho had devised a clever plan to prevent them.
No officer assigned to raise the barrier ever returned.
Finally Spirit World, in a frenzy as new souls poured through the doors, all confused and distressed and angry, managed to begin negotiations for peace between the two worlds.
Thinking to outsmart the childlike negotiator, Saicho agreed to call off his demons for a large sum in gold and jewels and a promising marriage for his daughter Claire. As Koenma had been about to agree, Saicho added one more condition to the agreement: Claire's husband had to be of all three worlds.
Koenma had reluctantly agreed to the final term as well – he had no choice. He immediately set off to search his files for someone – anyone – who matched that description.
He found only two. One was discarded immediately.
That one was Yusuke Urameshi. The human. The Demon. The boy who had come back from the dead… twice.
One month later an extravagant and large house was built on the human side of the portal, but near enough that Claire could go home and visit any time she wanted. A week after that the two were married.
It was a heavy blow to both the Spirit and the Human worlds.
Most of the demons followed their king's orders and left obediently. Others had to be rounded up and carted over the line. Still more were killed and their bodies discarded or burned.
Even years later Koenma would look back on that wedding and sigh. It was a political marriage, loveless and polite. Almost four years later the couple had their first child, a girl called Lilibelle for her maternal grandmother, Shiori for her paternal grandmother, and Minamino for her father.
Lilibelle Shiori Minamino.
Suiichi 'Kurama' Minamino's only child.
If it had been any one else there would have been no peace treaty. Kurama understood politics as much, if not more, than Yusuke did not. Where Yusuke would have argued and fought his way out, Kurama accepted his duty in stoic silence.
Youko the demon. The spirit fox. The human.
And so life went on. Rumours filtered through the levels of work until they reached Koenma's ears: there was something strange about little Lilibelle. When he asked Kurama if he could have a look at her, the kitsune had simply replied that Claire wouldn't let anyone but her parents near the child and that since Claire was the mother he had no right to contradict that decision.
And so Koenma had to wait.
He didn't have to wait long, he discovered. Only three years, in fact.