Katさんのイラストまとめ

Sehyuk also asked Ideun who is the person who was trying to kill him. Now let's go back to his family. Sungmin, the rapist, is not a real son of the CEO, making him a bastard son from a different man.

To be a bastard son, violated in his safe space, and being involved in 2 murder cases sure took a toll on his mental health and now he only has Sehyuk as his salvation to the point that if Sehyuk will drop the case, he will kill himself because there will be nothing left for him.

Being violated by his own family at his own home, he developed PTSD. This is based on DSM-5 Criteria.

Ideun directly experienced the event which happened multiple times. And not just the rape incident, but the murder incidents as well.

It was confirmed when the two met each other when Sungmin requested it and he raped Ideun again. Therefore, Ha Sungjoon is aware of what's happening behind closed doors and he just lets it happen.

Seeing his second brother, Ideun trembles in fear. Taking into consideration what Ha Sungjoon, the first son, has said about Sungmin having a certain "relationship" with Ideun, Sungmin could be the violator.

Ideun is always asking Sehyuk where will he go once he finished his testimonies--will he go to prison or will he be sent home? A home is our safe place so Ideun not wanting to go home meant that he is not safe in his own home.

Ideun is the only one without the syllable "Sung" in the name. It goes to show that he is considered the black sheep in the family and it was later revealed that he is a bastard son of the CEO from a different woman.

Let us look at Ideun's family
Father: Ha Sungyeob
First son: Ha Sungjoon
Second son: Ha Sungmin
Third son: Ha Ideun

Ideun seems to know Sehyuk very well and even knows his schedule and the passcode of his house. It is unlikely that Sehyuk told him the passcode, even the young detective was shocked at the thought of Sehyuk giving away his passcode to a murder suspect.

Ideun then asked Sehyuk probing questions which implied that Sehyuk entirely missed the most important detail of the incident.