Opening note: I am going to type Clark from Backrooms on Classic Jung, based on Psychological Types Chapter X. And as per my analysis, Clark comes closest to IS(T) personality type. Si (dominant function): As per Jung, Si is a function that orients around subjective factor of sensation. And dominant function is the most trusted and consciously differentiated function. Clark's life was broken as a man with broken marriage, dissatisfaction, lost job, etc. He discovered backrooms beyond his basement wall's invisible portal. And he saw it as being very immersed in it, believing in the sensations it evoked in him (subjective). There was some sensory effect that he found very peaceful and thus kept exploring it endlessly to later just settle there than returning to real life. While this is a typical unhealthy escapism, his trust on the subjective sensation points strongly towards Si. Te (auxiliary function): As per Jung, Te is a function that orients around objective logic. While auxiliary function supports the dominant function without replacing it. If there was one thing that helped Clark survive very long in Backrooms and understand why it made him feel better, it was mainly gathering of evidences. Like how one can consume the imperfect drawings that backrooms made like a real food, their descriptions, and the understanding about backrooms from its direct behavior, whether its about understanding how it remembers people, draws them, and then gradually forgets them. Instead if replacing Si, they aid it. Fi (tertiary function): As per Jung, Fi orients around subjective sensation. While tertiary function is an incosistent function which is less differentiated than the auxiliary. I consider the tertiary function in Clark as more important than auxiliary Te because he is shown primarily in the Si-Fi loop. In order to compensate for a failed relationship and job, affecting him, he chooses a sensory escape to backrooms. Fi comes into play because of the intense importance given to subjective emotional weight laid on himself, which later forces him to exit into backrooms to relieve the real-world worries and failures. Ne (inferior function): As per Jung, Ne is a function orienting around objective unconscious images. While inferior function is the least differentiated function which is subconsciously supressed by the dominant function, often pollutes by the contents of the unconscious. This fits Clark as he doesn't stop exploring the backrooms despite knowing that its endless and there is no point in exploring it. He ignores this larger pattern because the sensation backrooms evokes in him is what keeps him satisfied and drives him to keep moving. A higher Ne function would've led to questions involving what the backroom collectively is, and its objective essence, rather than being driven by sensation itself. Counter-argument against IS(F): It is very easy to be misunderstood as it comes closest to the original IS(T) type. However, we see an auxiliary Te instead of Fe. For Te I have already given the argument, now its time to debunk Fe. Fe is concerned with objective values. And auxiliary Fe would take objective values into account to support the subjective sensation, but Clark continuously disregards Fe. His failures were because he never accepted his mistakes, understanding values of others, and stood ego-centric. He blames wife for kicking him out and marriage failure instead of his drinking habit. Then he blames his boss for drinking habit because of extra working hours instead of his own desires, etc. Counter-argument against ES(T): This is the second most voted type across typology communities. But the problem here is that a dominant Se type is expected to perceive sensation as it is, closer to its actual form (objective sensation). While Clark was never interested in objectivity of the backrooms, but rather in terms of how it subjectively feels to him. That's Si. Moreover the auxiliary Ti would show signs of understanding the objective sensation with help of subjective logic. But Clark leads with more objective evidence-based judgement than making his subjective interpretations. This selarates him from ES(T). Counter-argument against IT(S): This one is argued too but drifts farther than his type. Reason is that IT(S) leads with Ti, which is subjective logic. A Ti-dom in backrooms would be more interested in interpreting the observations logically than being merely absorbed completely by the immersion it introduces. Clark was instead the latter than the former. Moreover the auxiliary Se in IT(S) is again not compatible with him because he doesn't rely on actuality of the sensation to interpret the mechanism of backrooms.