Set aside the WIP this week to take a few days and draft ...

Set aside the WIP this week to take a few days and draft out as much as I can for an idea I hope to sell.  The weird thing is I know the hero so well, but I'm not sure what his story will be about.  And I know the heroine not too much, yet I know where she must be by the end of this story.
So I just started on it a few hours ago, and have 15 pages so far.  I don't know what to write with this one.  Usually I go to a story and have a basic idea for scenes.  This one?  Nada.  It's all flying bli...