A is a ruthless mob boss. B is a fierce street kid who has suffered from parental abuse/neglect. After seeing B killing a man, A takes B under their wings and treats B as their child/successor, while B sees A as their parent.
Then A is murdered.
While B goes on rampage of revenge, he has discovered that A has a secret child C . B decides that C needs deadly trials and training so that he will be worthy of being A"'s child. C is both scared of and fascinated about B. Thus starting the new cycle
Then A is murdered.
While B goes on rampage of revenge, he has discovered that A has a secret child C . B decides that C needs deadly trials and training so that he will be worthy of being A"'s child. C is both scared of and fascinated about B. Thus starting the new cycle