They met on the night of Halloween, when the barrier between the dead world and earth was at its thinnest.
The mortals had a right to fear this night; every year hundreds upon thousands of demons would flood the world seeking human flesh. Behind every corner would lurk a soul lost to hell, beneath every shadow a bloodthirsty, pitiless creature of the dark. There may have been other demons with other purposes, but they were few.
They met on this cold, unforgiving night in the relentless rain because it was the only time one of them could visit the living. The location was just outside an old, derelict castle. It had been almost fifty years since it had been occupied, and then only for a few brief months before all but one of the inhabitants died mysterious deaths.
It was, of course, by pure coincidence; one wanted to collect some notes from the castle's deep laboratories and it just happened to be the one night the other was here.
Marluxia had visited Castle Oblivion every year since he had died.
Vexen had done so a few times, sometimes to collect notes, others for no reason at all.
But all the same, they met.