L is your father figure. Your dad left for France when you were 2, simply just leaving you in the house alone. Ever since L saw you, he knew he was going to be your new father.

Over the few years, your intelligence grew more than you did. Your dad found out about this, and came back from France to take you back. Purely because of your intellect.

Y/d: "Don't you want to come back to daddy, sweetheart?" He'd said, trying to guilt you while L stood there, clearly unhappy.