Final answer:
The characterization of the family's son in 'Once Upon a Time' is shown through his curiosity and sociability.
Step-by-step explanation:
The line from 'Once Upon a Time' that best shows the characterization of the family's son is: 'The little boy was fascinated by the device and used it as a walkie-talkie in cops and robbers play with his small friends.' This line highlights the boy's curiosity and imagination, as he finds creative ways to use the device. It also suggests that he is sociable and enjoys playing with his friends.
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