cheryskul
Thanos fights with his mental health and drug addiction everyday. His home life isn't the best, his father is an abusive, condescending alcoholic & he has a hard time looking after his little siblings all on his own while only working at a job with insufficient pay. He carries the weight of responsibility & pressure all while trying to keep his feet grounded despite temptation to give up.
Nam-gyu was a very sheltered individual growing up. Because of this he's had a hard time knowing and understanding people. Now in his adult years, he takes a social skills class on weekends in order to strengthen what he lacks. His parents divorced when he was little, leaving him with just his dad & a very strained relationship with his emotionally unavailable mother whom he hardly sees or wants anything to do with.
Both of their world views clash, but they learn a lot from each other, & despite their differences they eventually catch feelings. Only one can never tell if it's one-sided due to the other's struggle with feelings.
Story is also on AO3 (@cheryskul)