I saw backrooms last night and one thing that I actually didn't love in the movie that I've not come to really enjoy was how quickly clark goes kinda crazy in there.
I do still wish there was one or two more scenes included that I think would have made me enjoy it more on the first watch, but I think its really interesting how for most of the movie even though we know clark is a shitty husband and a shitty boss we don't know HOW shitty he actually is.
For majority of the movie its extremely plausible that clark is just a run of the mill douche bag. Sure he yelled at his therapist at the beginning but its therapy! Mary even tells him its the point of the exercise for him to get angry like that! No big deal! And yea he's rude to kat and bobby when filming the commercial but he's clearly frustrated about business and that he just broke a chair with his ass in a silly pirate costume. That scenes might even feel relatable for many people in the audience with shitty jobs.
And then when he's exploring the backrooms for the first time he almost has this childlike wonder about the place. Where most people would reasonably just not go back in he's getting so much delight from finding something he thinks is pretty important and using his architect knowledge to map the place out. Yea he's reckless with Kat and Bobbies lives but even that feels like Clark is just So! Excited! To Explore!
And then hes strangling Mary. And then he has her tied to a chair. A chair that's in his fake family doll house of these backroom still-life's, with his sort of ex wife standing at attention in the corner and these people he seemingly doesn't know from his real life that he's taken as friends? New family members? Whatever he is using them as stand in's for it is definitely not whatever they were originally "made for" in the backrooms.
I think it serves as such an ice bucket drop on the audience of how horrible Clark really is as a person. No he probably wasn't tying his ex wife up outside of the backrooms or anything like that, but he almost certainly commanded their home like she was. Clark is fundamentally a broken man in someway who's desperate to feel normal? In control? Powerful? A mix of all three and more? Clark is given the tools to create those feelings for himself though by the backrooms and literally JUMPS at the opportunity. At first I thought there had to have been a time skip before this scene that I missed but no, Clark literally turns to this new lifestyle in the backrooms the second he meets his own backrooms memory.
TLDR: Clark is every man ever who refuses to take accountability for their actions and resort to weird justifications and violence.