First of all, thank you for the feedback, everyone! The consensus seems to be giving the player a lot of options and opportunities to interact via MC. One of the gameplay aspects I've been considering was allowing the players to implant triggers on hypnotized characters, which should work fairly well towards that goal. So I'll definitely try to include that in my text adventure.
Zermelane said:
How to do that in practice, I don't know. I'm writing this off the cuff so I don't even have any examples of particularly good or bad scenes to show. But for a start, at the level of just looking at single words: I'd consider any use of the word "mind" (the noun) suspect. We don't experience our minds, our minds are our experience, so if you're describing something happening to the player character's mind, there's probably a more direct way to say what you're trying to say. As a bit of a more personal pet peeve, "pleasure" is a word that covers a lot of sensations in a way that makes it easy to overuse. I'm not saying that either word should be tabooed, those are just the first few I could think of that that I see used badly a lot.
I have to partially object to the idea we can't experience our minds, because we do have a certain degree of self-awareness. We can tell when we're mentally tired, whether we're focused on something as opposed to bored of it, and so I wouldn't exclude it altogether.
In the particular case of hypnosis, all of my experiences being hypnotized I felt an objectively different state of mind, I usually describe it as being stuck inside my own head. But from an artistic point of view, I can understand where you're going. It's difficult for a reader to feel mind controlled when they're not being mind controlled (as far as we know), but it's easy for them to appreciate the sensations that might come with it.