I definitely have the same feeling as you. I knew KJW the first time from Coffee Prince in 2007 and was so impressed by his black nail color. But I didn't feel anything about him and did become a fan of Gong Yoo.
Then among all these years, I skipped all his dramas as there is an attraction to me. Then I happened to watch HPL and surprisingly find that after so many years, KJS becomes so sexy and hot. He got talent for comedy also, which is a contrast to my old impression for him. And I watch BTS also. He is talkative and laughs a lot, not as cool as what he looked like to be when he was young.
It took 12 years for me to become a fan of him!!!
I also finished VOICE recently. I guess I would fear of him if I watched VOICE before HPL as he is really a psychopathic in this project