[SPOILER] Plot Discussion Thread *Spoiler Alert*

[Alardem]

I think that's a red herring. The conversation between Mandus and the Professor would lead one to believe the Engineer is a separate entity from Oswald. However, the payoff arrives when the Professor gets to 'meet' the Engineer - as it turns out, that means he gets attacked by Mandus.

The interview with Pinchbeck linked back a page ago says that extra notes were provided to emphasize Mandus' split personality in order to make him more sympathetic to play-testers. Most memorably for me, that leads to the note of Mandus masturbating to the image of his dark twin - the Engineer - in his mirror

Therefore, the Engineer WAS part of Mandus: the brilliant, murderous and inhuman side of him. It's also possible that the Engineer is the engine through which the Stone Egg works its dark magic on Oswald. The Engiener's relationship to Mandus is similar to Clarence's symbiosis with Philip, in that they are both darker portions of the protagonist's personality who are born through supernatural catalysts, corrupt their hosts, and eventually take on lives of their own.

Therefore, the flashbacks between Mandus and the Engineer exist in Mandus' head - a mental conversation between him and his darker personality. The reason for having different voices is artistic license. It'd be even more confusing if Mandus and the Engineer's voices were the same, just as how Clarence's voice is quite clearly not the same as Philip's.

@MyRedNeptune

I disagree quite severely about the characterization being implausible. Mandus' actions boil down to a mixture of obsession, repressed hatred and class warfare, all bound together by the cultural context of the industrialized Victorian period. He's certainly insane, but it is an insanity that can be understood much more than, say, the Joker from The Dark Knight. He's not to be dismissed as generically crazy, given that a significant portion of the story is about understanding his motivations.

Also, Alexander was driven by desperation and lost love, not because he was an inscrutable Cyclopaean horror.

It all boils down to how much thought you're willing to invest into the story. If you didn't enjoy it, then you won't spend much time trying to make sense of the information you were provided. You may call it over-analysis, I just call it part of the fun. Making logical sense of gaps in a horror story can make it more enjoyable. If I apply your surface-level reading to Daniel, I can say that there's no logical reason why he jumps from 'scared archaeologist' to 'gleeful torturer/child-murderer' when given little evidence for the value of his crimes other than the word of his friend.

Not to defend poorly-written stories, of course. I recall FEAR 3 as an example of a story where in-universe consistency is nonexistent, making trying to understand the story a futile gesture because it was evident the writer himself didn't put much effort. And Bioshock Infinite? I can go on about how it tries to throw all manner of interesting ideas to make itself appear deep on a surface level, only to discard them before any further analysis can be made in favor of a thoroughly inane ending that tries to amaze through confusion. My point is that there's a difference between being deliberately inscrutable and just plain bad writing, and Pinchbeck's is the former as far as I'm concerned.