Your personal Tumblr journey starts here
So, this is a theory about Kunikida's past and why he is so aggressive...Don't rush to kill me, I'm just guessing
Perhaps Kunikida grew up in such conditions that aggression became something normal for him. Nothing is known about his childhood, but... I can guess a couple of details.
Most likely, physical violence was used against him. There is a possibility that Kunikida grew up without a father, because...Rokuzō has a father who dies. Kunikida feels guilty for this and tries to look after Rokuzō. This may be a consequence of the fact that Kunikida himself experienced something similar and simply does not want anyone else to suffer from it. If Kunikida was treated badly as a child and already in adulthood he behaves SO responsibly, then he could have lived in such conditions that he had to grow up early. And if we add the possible absence of one parent (most likely his father), then it turns out that Kunikida had a bad relationship with his mother. This leads to the theory about those unknown 58 points...maybe Kunikida is just looking for someone who won't be like his mother. Even externally. Cuz, look,Kunikida had a short romance with Sasaki. That is, she is technically the only character who somehow fits these 58 points. Sasaki has black hair. Kunikida is blond. Maybe he is like his mother in both in appearance and behavior. Children may unknowingly act like their parents. So, Kunikida is aggressive because his mother treated him that way.
I know, I know. Most likely the theory is extremely stupid and illogical, but... I tried.