Taem1n is a little bit autistic and awkward. He laughs and smiles during the pain. When it's bad, he has a tight-lipped smile that's painful to see. He won't do anything to rock the boat. During Sup3rm promotions, they played a prank on him and Loocas. He was clearly uncomfortable with the situation but tried to smile and laugh it off. He's not charismatic like Key or Minh0.
There's stage Taemin, a persona he puts on for the audience, an there's L33 Taem1n. The latter is a serious person, who is awkward to talk to when the conversation leaves a script. Unscripted Taem1n is both painfully cringe and very endearing. I love those moments the best.
I can't convince you he's not a monster, and if it were him instead of Jjon9, I would probably feel the same way about the members. Taem1n wrapped his idol persona close around him, and relies on it to interact with the fans. The few times we see him unguarded, it's like a different man. Most idols do this, but can communicate normally if their guard is down.