In the following phrase:
The film offers a considerable number of long takes, making use of the technique to lace the film with comedy but also to quiet the need for more energetic forward movement of plot so that the subtle exchanges between and among characters might resound more deeply.
Why would the author have written “between and among” in this way? I understand the meaning of “exchanges between”, but not the meaning of “exchanges among”. What is the difference, whether real or implied, between those two terms here?