Run On tells the love story of Ki Seon-gyeom, a former sprinter who is working to become a sports agent, and Oh Mi-joo, a subtitle translator.
Im Si-wan plays Ki Seon-gyeom. He is a professional runner who also quite socially awkward.
Shin Se-kyung plays Oh Mi-joo. She is a foreign film translator and subtitler.
Sooyoung plays Seo Dan-ah. She is a president alpha bitch but shows signs of a hidden heart of gold.
 Kang Tae-oh plays Lee Yeong-hwa. He is a university student and talented artist.

I enjoyed the stories of both couples, they made me laugh and I thought they were cute. Also, I realized: sometimes it’s okay for a couple to just click and work, without all the fuss and dramatics, you know? It never felt like their respect or feelings for each other were in doubt or denied and I appreciated that. I think the second couple had more intensity but they (Dan-A) were more frustrating. I think I didn’t mind it because they weren’t the true lead/priority in the storyline, but if they were it could approach the border of toxicity. I do think the first couple is more likely to survive a pandemic together and that’s the way I judge how I feel about couples now.

Sun-Gyeom learns how to let the people around him in (friends and romance) & let people care for him like he cares for others. Though, I couldn’t tell if his obviousness was natural or forced to deal with the toxicity his family brought brought onto them. Also, re: the reason he left the sport: why so righteous?
I loved how Yeong-hwa eventually demanded respect from Dan-A, who also learns how to treat people better, all while remaining true to herself.