Fractions? I don't think I've heard of that term before, other than meaning such mathematical terms as 1/8
I think we already had a lot of discussion on the topic of romance and pairing here
http://forums.animesuki.com/showthread.php?t=8866
I don't think there is going to be any pairings actually shown between any main characters. Maybe hinted at. UsoppxKaya is definately hinted at, but not certain. I'd say if ANY pairing does happen at the end of the story, it's that one.
I just like pairings in a fun, fandomm sense. I always will like UsoppxNami, though it's not like I'm actually expecting it in the story.