Because you like Maria von Trapp in The Sound of Music
Dolores Umbridge keeps her villainy hidden (albeit poorly) behind a sheen of sugary pink politeness. See them in Harry Potter Series.
There's more to this sweet, caring landlady than meets the eye. See them in Sherlock.
Juliet Capulet falls head over heels for her rival family's resident sweet talker, Romeo. See them in Romeo & Juliet.
Wanting more out of life, Pam Beesly has a job she isn't crazy about and is engaged to a guy she's not sure is "The One." See them in The Office.
Alex Danvers is a brilliant engineer tasked with alien threats, and one of those aliens is her adopted sister Supergirl. See them in Supergirl.
Frodo might have carried the ring, but Samwise Gamgee carried the ring bearer. See them in The Lord of the Rings.
Andrea Sachs' boss is not happy unless everyone around her is panicked, nauseous or suicidal. See them in The Devil Wears Prada.
Donna is boisterous and spunky traveller of the TARDIS, exploring worlds beyond the simple mundane enterprises of Earth. See them in Doctor Who.
A karate master/rocket scientist/squirrel, Sandy Cheeks is the only one who can clean up the other resident's messes in Bikini Bottom. See them in SpongeBob SquarePants.
How lucky are we that Arthur Curry, the King of Atlantis, hasn't taken over the surface world? Very! See them in DC Extended Universe.