I have to give a shout out to one of my favorite Syd/Vaughn authors:
CaptainSwanLuver's Fan Fiction
I remember Steph from the Syd/Vaughn fan fiction yahoogroup. Every single story of hers was so in character and so beautiful that I didn't even mind they only had a PG rating.
I completely recommend any and all of her fics to you.
Enjoy!