Who is PIC

This might be one of the most important questions pilots can ask when flying with other pilots (other than multi crew aircraft).
Even Mary (the DPE and 40 yrs. of experience) and I (the daughter with half the experience) often ask before a flight. Now on the surface it might seem Mary makes the better pilot, and wile that's not wrong, sometimes I make the better pilot. Sometimes I am more familiar with the aircraft and or the route, sometimes I'm the one rested and prepared for the flight. Unless its her plane!
Even if I am not the most experienced pilot she would do a better job of coaching me through an emergency situation than trying to take over and do it herself increasing her workload. Not because she is somehow less recent in the flying but because she has the most skill and able to keep the big picture going, while I focus on things like airspeed and direction. If I became focused on one item too long allowing another to falter, she can see it quicker than I will.
Once PIC is established next rule should be the conservative voice will win. So when you and your pilot friend approach weather, and the PIC says lets keep going, and the non PIC says no, then the answer is no do not keep going, This could even be true of the Newbie pilot PIC (her plane) and the other pilot with her is a heavily experienced pilot supposedly. Same situation but this time the lower time pilot says nope going to land, the non PIC begins intimidating them into going further. Conservative voice should win again. (flight instruction properly done doesn't count here, its often our job to push those comfort zones some).
I call those pilots bullies, and you wouldn't let such a person fly and push your child or friend into bad situations in the air, you definitely shouldn't let them do it to you.
Once you have established the rules of the flight (on the ground of course), now you can enjoy the flight and so can they.
Go Fly The Plane!