Both Shadow Darners and Happy-face Darners (Paddle-tailed Darner) were present, but only males were seen. The interaction between the males seems more intense than in the middle of the season, when females are numerous. This time of year the males seem desperate to find a female, and as a result are more aggressive with one another. I also get the impression that sometimes one male grabs another male hoping it might be an andromorphic female. In any case, the males are grabbing hold of one another this time of year much more than is seen earlier in the year.
Here's a video showing two males that grab one another, spin around, then fall into the water. They both get out and fly upward.
A third male observing the interaction flies upward too, and then does a wonderful aerobatic move where it rolls 180˚ and pitches in the dorsal (positive) direction. What a nice maneuver. In aerobatics, this is referred to as a split-s – basically, an Immelmann turn in reverse.