The Fool (spoilers for all RotE books, including LST)

[Lady Persephone]

It began to dawn on me that, in my own opinion mind you, I believe the Fool and Fitz did go beyond friendship and perhaps didn't even fully realise they were doing it when they became one during Fitz's healing of the Fool and becoming him in FF.  I believe for the genetic information for a White to be passed on it takes such a bonding, such a oneness with another which could be how the Fool himself was conceived by two fathers in the tradition of his species.  I forget the exact line the Fool said about that but later on when I'm at home this evening I'll try to dig it up. 

OK, sorry this took forever but I finally did manage to dig up the passage where the Fool discusses this with Fitz.  It's in Fool's Quest, chapter 18 "The Changer" pgs 330 - 332:

'Of course,' he whispered at last. 'It would have to be so.  I understand it all now.  Who else's could she be?  In that moment, when she touched me, ah, it was no dream, no illusion or delusion.  I saw with her.  My mind was opened once again to all possible futures.  Because yes, she is Shaysa, even as I once was.  And I did not see her in the futures I glimpsed for you because, without me, you would never have had her.  She is my daughter, too, Fitz, Yours and mine and Molly's.  As is the way of my kind.  Ours.  Our Bee.'  

I was torn between utter confusion and deepest insult.  I had a faint memory of him telling me once that he'd had two fathers, brothers or cousins, in a place where folk accepted that arrangement.  [Skipping some rambling from Fitz here] 'Fool.  Bee is not your child.  You were never with Molly.' He smiled at me.  'No, Beloved.  Of course I was never with Molly.' His fingertip tapped the table, once, twice, thrice.  He smiled gently.  Then he said, 'I was with you.'   [skipping a bit here] 'Fitz.  You can deny it.  But I have been with you, in every way that matters. As you have been with me.  We've shared our thoughts and our food, bound one another's wounds, slept close when the warmth of our bodies was all we had left to share.  Your tears have fallen on my face, and my blood has been on your hands.  You've carried me when I was dead, and I carried you when I did not even recognize you.  You've breathed my breath for me, sheltered me inside your own body.  So, yes, Fitz in every way that matters, I've been with you.  We've shared the stuff of our beings.  Just as a captain does with her liveship.  Just as a dragon does with his Elderling.  We've been together in so many ways that we have mingled.  So close have we been that when you made love to your Molly, she begat our child.  Yours.  Mine.  Molly's.  A little Buck girl with a wild streak of White in her.'

 God I love these books!  I love the depth of emotion and feeling and beautiful expression of deepest love that Robin Hobb infuses into them.  She writes her heart and out it flows.  This is why we love them so--sleep, breathe, and eat these books.