Saruhiko Fushimi was shaped by his parents though they were more biological donors than anything else. Neither of them really cared about being married or having a family. They formed a marriage that was financially and socially beneficial without any actual love. Neither felt affection for each other and they didn't put much effort into showing Saruhiko affection either. Instead they rleft him to be raised by a household staff.
Although neither of his parents were stellar role models his father,Fushimi Niki was far worse than his apathetic mother, Fushimi Kisa. Kisa was a big time business woman who had her only son at the age of nineteen. She didn't feel he was her responsibility and often left him under the care of Niki. When Saruhiko left home she cut him off and abandoned him.
Saruhiko's father was emotionally abusive and took joy in tormenting Saruhiko. From the moment he was born everything his father did was in an effort to make him miserable. Niki named him Saruhiko because he and "looked like a disgusting monkey". He would come home once a month from some mysterious job and tease his son every time they crossed paths. Niki came home one month when Saruhiko was young and set an ant farm Saruhiko was using for a project on fire along with his journals recording his findings. He then dropped cockroaches on the remains. That day he taught Saruhiko two things that would shape his future. First, he fostered a fear of fire and second, that anything he cared about could be taken away. When Saruhiko was in middle school his father became ill and his mother urged him to visit him because he was his father "genetically speaking". Saruhiko did not heed her advice and often tried to push his abusive father from his mind.
Saruhiko had an extended family although he wasn't close with the majority of them. His grandparents, aunts, and uncles only cared how he did in school and he only had one cousin his age, Oogai Aya. Growing up Aya was often jealous of her cousin who she was compared to by relatives and found lesser simply because she was a girl. She sought to make Saruhiko recognize her as his better which was a difficult task considering Saruhiko couldn't be less interested in her or anyone else in their family. In middle school she would occasionally hang out with Saruhiko and Misaki and brought them along on missions she was doing for ≪jungle≫. She resenting Misaki for taking her cousin's attention when she tried so hard to get it.
Saruhiko and Aya became distant when Aya graduated and moved on to high school while Saruhiko joined Homra with Misaki. It wasn't until a year or two later when Aya began using a virus ≪jungle≫ installed on Saruhiko's PDA to make him hallucinate his father. She tormented him as his father did until he finally beat her. Even then she resented him for catching the interest of the green king.