Character Quality - Static.
Character Arc - Flat.
After reading my book "Character Matters", a few of my contacts asked me about the practical usage of those methods in movies. I am sharing a piece of my research for your eyes.
Director Prem created his Prime character "Ramachandran alias Ram" under the Introvert Personality trait. Also, this character is one of the best examples of a "Flat Character Arc". The story is all about an Introvert's love. Under the four shades of introversion: social, thinking, anxious, and restrained, the director created "Ram" as an anxious person. Introverts, like any other personality type, fall in love at a pace that is subjective to each individual. However introverts, unlike extroverts and ambiverts, don't share how they feel with everyone around them.
It has taken several years for Ram to get into Social Media and get connected with all of his schoolmates. They require one good triggering point to get from A to B. The territory character played by his student takes him to his school accidentally. Which pulls his buried memories to the deck.
Ram always lives and cherishes his memories. Scratches his wound every time to feel the pain. Flat characters do not change during the story. If Ram would have been in a positive arc, he would have gotten married to Janu. If he is put in Negative Arc, he would have killed Janu. Introvert characters with flat arcs are always harmless.
A static character is a type of character which largely remains the same throughout the storyline. The environment may change, but they retain the same personality and outlook as they had at the beginning of the story. It's common for secondary characters in stories to be static. But Ram as a Protagonist lives a static life from the beginning.
The journey of Ram is memorable to the audience just because he is harmless to anyone but only to himself.