Greg Pak 
Firefly #33 [PDF ebook] 

What happens when your worst enemy becomes your only ally? With her sights set on freeing Leonard, Kaylee’s team chases the Jefa across the Earth That Was only to be led directly into a trap. But everything changes when they get attacked by plunderer robos who have been tracking both groups to exterminate them all. Now, Kaylee must team up with the Jefa in order to fend off the robos. But if they survive this, how will they survive each other?