So I’ve seen the movie about 20 times. I’ve listened to both commentaries on the 10th Anniversary DVD and understand a lot of character motivations for why Archer and Castor Troy did the various things that they did. I understand why the writers fought to have various scenes kept in (such as Castor as Archer sleeping with Archer’s wife) and various scenes kept out (such as Archer as Caster sleeping with Sasha). Basically, I’m saying I’m familiar with the movie and have thought about this question. The one thing I can’t understand is why Castor as Archer tries to shoot his own son during the raid of Dietrich Hassler’s loft. From the previous scene with Archer as Castor and Sasha, I think we know that Castor did not know the kid was his son. But either way, out of all the possible victims he could shoot especially considering he has Archer as Castor in his sights before that, why do the filmmakers have him aim and try to shoot the kid (even if Dietrich unknowingly gets in the line of fire and takes the bullet)?
I think it’s because Castor had killed Archer’s son years before and he wanted to make Archer relive that right before dying.