The most popular movie entertainingly depicting multiplicity of inner psychological systems is, of course, Disney Pixar’s “Inside Out”. Here are some other less well known options if you’re hungry for more!
“It’s Not You, It’s Me” (2013) is a rom-com directed by Nathan Ives — it has very clear depiction of parts in the inner world of an on-off couple.
“Reason and Emotion” (1943) is a Disney wartime anti-propaganda short which has dated somewhat but is still interesting to see in its cultural context.
“Brain Divided” (2013 animated short) also depicts parts in a romantic scenario — a date!
“Only Yesterday” (Japanese, animated, 1991) In this touching and slow moving Ghibli movie, parts aren’t as obviously depicted as in”It’s Not You, It’s Me”. Rather, we see a young part’s impact and story juxtaposed to the present life of the main character.
Can you think of any more examples?