What makes this storyline brilliant is the power dynamic. Ava is usually the chaotic, incompetent principal, but here she holds leverage over Jacob. It leads to one of the most memorable recurring gags of the series: Jacob being forced to do grunt work while Ava holds his vape hostage.
Gregory is still adjusting to being a long-term sub, and Barbara takes him under her wing in a way only she can—with strict boundaries and honest truths. We see Gregory realizing that teaching is harder than he thought, and Barbara showing him that experience trumps theory. abbott elementary s01e09 bd9