The first one the came to my mind was Once We Were Gods (Season 3, Episode 15.)
We get so many good interactions this episode!!! My favourites have to be the scene between Alexander and Nick in the car, and the one between Adalind and Meisner in the cabin.
(Other episodes that come close are The Bottle Imp, Where The Wild Things Were, Breakfast in Bed and Stories we Tell our Young.)
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