An adaptation may give one screen character work performed by several people in the book. Counting the missing names is a start, but it does not show what the combination changes.
Map actions rather than personalities
Choose two or three scenes and record who delivers information, creates an obstacle or offers help in each version. A simple table can reveal that the film keeps an event while changing the relationship through which it happens. Avoid assuming the combination had one particular production motive unless a reliable source documents it.
Watch the consequences of accumulation
When one person becomes messenger, confidant and opponent, they may appear more central or inconsistent. Check whether the film supplies transitions that make those roles fit together. Compare what the viewer knows about that person before each action with what a reader knows about the separate characters.
End your note with one consequence, not a verdict on faithfulness. “The warning now comes from someone the protagonist already trusts” says more than “three characters were removed.” It also invites a discussion about how the adaptation reorganises trust rather than treating every reduction as automatically a loss.
