Diluc presents himself as the epitome of perfection. If you can get past his fake acting to hide his identity, he has a gentle, tender, and modest nature. He became a murderer after experiencing trauma from his childhood, making him a sociopath. He is not fond of alcohol as he does not like its taste, and it clouds his mind when he works. He prefers non-alcoholic drinks. 

He works as an office worker by day while he kills by night. He lies about being an office worker to hide his crimes.