I wondered if Karen had been created in order to track down Leo and the other synths. Her purpose is to be a detective, but, being a higher order synth she is curious about human feelings and sexuality as well.
Like other posters I wonder if Leo has the full picture. He says he "died" when he was 13 because his mother tried to take him away, but he says that his father wasn't able to digitalise all his memories. I wonder if David E. chose which memories Leo would retain in order to keep the truth from him. Is it possible that Leo's mother wasn't mad, but was worried about David's mental state and his attempt to replace normal human relationships, a mother, a teacher, a brother, with synth ones in Leo's life?
Do we really know that either Leo's mother or father are dead? We, and Leo, cannot rely on his memories as it was possible for David to edit and manipulate them.
If David E. is dead, then what was the reason for his suicide?
If Leo's memories have been manipulated then does Mia, as the oldest synth, hold the key to what actually happened?
Is this why she was reprogrammed and her memories suppressed?
Now that her true personality and memories have surfaced, will she remember more about Leo's childhood and why his mother was shut away?