Characters in opposite relationships are forced to change. They cannot remain stagnant because their partner constantly challenges their worldview.
While not always "opposites" in personality, these characters are opposite in intent . This storyline relies on the "thin line between love and hate." The intense passion required to despise someone is easily redirected into romantic fervor once a common ground is found. Why These Storylines Work The Opposite SexHD
If you look at the most successful romantic storylines in media, they almost always utilize specific "opposite" archetypes to create narrative drive: 1. The Grump and the Sunshine Characters in opposite relationships are forced to change