Question: When Norman says the guy "that wrote that book he loves" (Shumway?) congratulated him on Spencer's Theorem, then Claire says "He didn't know your father was dead?" and Norman says "He knew". What does one thing have to do with the other? I've seen this movie at least 20 times and I can't figure out this conversation.
Question: If Norman married Claire when she was "touring with a baby" (Caitlin), why is he not referred to as Caitlin's stepfather? When they take her to college, Claire refers to him as "Norman" when speaking to her. I've seen the movie a few times and always thought this was a little odd. Many people would even think of a stepfather as "father" if he was the one who raised them for most of their life.
Answer: There's no rule about how a step-father is referred to. Caitlin may simply not consider him a father figure and is close to her real dad. Most step children call their step-parent by their first name, regardless of how long the parents have been married. Most likely it's a plot device so that the audience isn't confused about or doesn't forget that Norman is not Caitlin's real father. Some may be offended by a father killing his biological child's mother. It makes Norman less attached to either Claire or Caitlin.
I am not trying to be rude, but have you seen this movie? You say that Caitlin might be close to her real dad. He is dead. Claire was "touring with a baby" after he died, and then she met Norman. Hence why I found the situation a bit odd. Norman has been in Caitlin's life since she was a "baby."
I saw the movie some years ago and don't remember every small detail. However, my main point was that calling Norman by his first name was a plot device to keep the audience focused on him not being Caitlin's biological father. This kept his character more detached from Claire and Caitlin, and made him less sympathetic. It showed an emotional/personal divide existed between Norman and Claire and her daughter. He has less resistance in killing Claire if they did not share a biological child.
Chosen answer: Spencer's theorem was Norman's father's theorem. Norman wants to be greater than his father was, so to be accidentally complemented on something that his father did would be bad enough. To say that the guy knows that his father is dead is to imply that the guy probably insulted him intentionally.
Myridon