David M. Booher 
Firefly: River Run [PDF ebook] 

Simon Tam will do anything to save his little sister from the Alliance. It’ll cost him everything- his wealth, career, parents, and a perfect life on the Central Planets. But the love between them, a love more dangerous than madness, will persevere as Simon goes undercover into the Alliance to get her away from those that hurt her at any cost. In addition, it’s time for a Christmas Carol, Firefly style! Jayne’s selfish behavior receives the unwanted attention of three visiting spirits who reveal the hidden past, present and future of Serenity’s most miserly crew member. Collects Firefly: River Run #1 and Firefly: Holiday Special #1.