Both characters have doppelgangers.Both are melodramas that are a little dark.

Both are revenge dramas, and both deal with very mature subject matter. Qoa, death of a child, missing you deals with rape and other really touchy issues.

I watched secret first and it's one of my favorite revenge dramas, but I have never seen such a blood boiling drama in all my life as QOA.

Both have KSW and both are great love stories. However, bad love doesn't have the same hatred. Lol