Dramas where side character stole the show?

For me it's Pasin  aka Kim Min from A Shop for Killers

Choi Gyu Ri in Marry My Husband changed me, such a sweetheart. Excited to follow her work as she works on more projects

Who Are You: School 2015 - SML Kong Tae Gwang was much more likable than ML Han Yi An

Dali and the Cocky Prince - the ML's female assistant - she is a very minor character but has visible reactions to everything going on, often hilarious. I kept looking away from the main characters to see what she was doing.

CRASH LANDING ON YOU: 

In the second half (from around ep 9 when FL went back to south korea) I was more interested in the secondary couple (seung joon and seo dan) my rating dropped more because they didn't end up together T_T