I think it has something to do with the family of four
Is it a coincidence or… did someone purposely keep them at a place that would be safe from the fire? Chen Ge felt like he was on the right track. The only person who could that… is the killer themself! But why would the killer risk their life to protect these four dolls? Are these items of importance to them?
I just realize even though he has all time he need to practice or learn everything yet he didn't,for example like calligraphy,languages,self defence,music and etc