Dauntless has a fun acrobatic twist. I can't tell you how many times I've read about medieval "acrobats" in historical text books. So, I never thought to ask if the word acrobat actually existed at the time. But right before sending out my final version of Dauntless, my daughter's skepticism about the acrobats prompted me to do a little more last minute research. And...I found out the word "acrobat" actually did not exist in English at that time. They would have been called "tumblers" or possibly "aerialists" if they worked off the ground. When used in military training, acrobatics would have been referred to as "agility skills." Mind you, since they spoke Middle English in 1216, I'm fairly lenient with myself on using words from as late as the 1600s when the language stabilized. But "acrobat" wasn't around until the 1800s.
In my last minute research I also found this cool video of medieval "tumblers." If they claim to be "acrobats," don't you believe them!