Ego Man #1

Principal actor, after doing three very easy, brief takes (during which the words he was saying were actually only paraphrases of the lines in the script), when it was time for the turn around (getting the shot from the opposite side) to shoot his scene partners: "I'm not doing that whole scene again all the way through."

Director: "...Ok, you don't have to."

AD, under his breath: "Well, do you want [the other actor] to be reacting to anything?"

The actor got his way, and for the next two days, any time there was a turn around on a scene of his, the other actors reacted to the AD either narrating the action or reading his lines (while he played with his phone off to the side).  Not once did that principal stay around to help out his scene partners.

I looked up the actor afterwards. Turns out his previous roles are mostly characters identified in the credits by their function description, sometimes with a number in their title (the type of role listed in the credits as "Drunk man #2" or "Office worker #1" or "Frat boy #3") -- respectable under-5 roles, but not anywhere near the career level needed to justify never acting in turn arounds for your scene partners (if there is a career level to justify always doing that to your scene partners).

And with behavior like that, I imagine he has a long career ahead of him of numerically job-named characters.  Hopefully that includes at least one job where he has to react to an AD reading his scene partner's lines while he stares at a PA's hand as a focal point.