You have experience-does each aircraft have a designated “Flight Commander” with authority on the aircraft, or is that a dated reference on my part?
In an aircraft that (by regulation) requires two pilots, one is titled "Captain," and is in "command." This term applies in the U.S.; other countries and languages may have different terms.
The owner of the aircraft may require two pilots, even if the authorities do not. That pilot may wear four stripes.
"Professional flight schools," those who turn out commercial pilots used to weed out the "cry babies," (male or female) but I'm guessing affirmative action quotas have done away with that practice in some countries.