There are some where the partner needs to be dominant. And others where they need to be submissive. Or they need to prefer topping, or bottoming. I am missing a bunch of Toru's from the first play through because he was just Sub/Bottom. And I missed a couple on Shiba cause I turned him Dom/Top, and I'm pretty sure he needs to be Dom/Bottom to initiate one of them. At least bottom for sure cause it's an initiated one based on the same location I unlocked on Toru. Just like the Top-Left one has to have the partner as dominant and that gets missed a lot with the naturally submissive characters that you don't take the time to encourage to another style.