Anyway, I was surprised by the lack of Yuki/Sojiro fanfiction. So far I've looking thru like a hundred stories and only found one Y/S, which was actually pretty good. Here is the link if anyone is interested:
Uncatchable Stars by Chi5
I think it takes place like a year or two after the manga ends and it is really cute and beautiful. I highly HIGHLY recommend it for any Y/S fans.