"Doctor Frost" Song Jong-ho, a grudge against Song Chang-ee?

 What is the relationship betweenSong Jong-hoandSong Chang-ee?

The eighth episode of"Doctor Frost"showed Sang-won (Choi Jeong-woo) being hostile towards his old student Seong-hyeon (Song Jong-ho).

Sang-won had pointed out Seong-hyeon responsible for the Oh Ki-eok case. Seong-hyeon had just come back to the country and he tried to get Seon (Lee Yoon-ji) involved as she was good at what she does by connecting with people.

Seon was happy to take up his offer but not Sang-won. He told her Seong-hyeon was not to be trusted and advised her to cut him ff.

He then met with Sang-won and said, "I am a scholar so I can't fight with anyone. Still, I won't have you mess around with my student". Seong-hyeon coldly responded, "I am your student, too".

Frost didn't know about Sang-won's speculation yet. He told Frost, "I will tell you when I am sure of what I'm thinking".