Both Kdramas are about agents, and the vibes are very similar. Terius Behind Me is about a single mom who somehow gets involved in top secret missions. The K2 similarly involves secret missions. Although The K2 is more about a wealthy girl and a bodyguard, like Terius Behind Me, it involves a love story around the main female character and the bodyguard which is why if you liked Terius Behind Me, I strongly recommend watching The K2.

I personally watched The K2 first and had been trying to find a drama similar to The K2, but after years and years, I finally found Terius Behind Me and definitely don't regret watching it.

Both dramas are about doctors, and saving people. Doctor John is about a man named Cha Yo han (John) who was sent to prison for a punishment. One of the guards niece (Kang Shi-young) is used to be a doctor who came to the prison because the former prison doctor had quit. After John gets releases, he becomes a professor at the hospital where Shi-young works and also the hospital where her father is laying down trying to recover from a former hiking accident. Doctor Yohan is an extremely talented doctor who can figure out what is wrong with the patient within seconds. As Kang Shi-Young and Cha Yo-han are both talented, they are also trying to move on from their dark past.