These are the moments that make me truly love cosplay. When a character variant meets up with a gender-swapped version of the more traditional character, magic happens. If you don't recognize these two, then you probably aren't familiar with Firefly, which means you have much bigger problems than not recognizing two awesomely dressed people at a convention.
And there are two people who have not seen [i]Firefly[/i]?!? What are the odds of them both being readers of this blog? Get them the DVDs, stat!