Go a step beyond that and tie in fetishes to characters and locations.
-Rogue is the vanilla girl. She's there for you to test the system with and who's major kink is the addiction focus, more addiction = more sex even at lower affection. You need to get Rogue's permission to start building the harem otherwise she takes a massive affection hit.
-Kitty has a hidden submissive side you have an inkling with when you grab her and don't get go in meeting her. Her kink unlocks a dungeon and bondage gear for all the girls.
-Emma is a repressed exhibitionist. She alludes to this when you catch her in the classroom but doesn't want to take things further than that. Her kink is her getting to accept that she likes being looked at and telepathically projecting clothes while nude is a step in that, eventually she'll just not wear anything at all unless Zero is being called "Master" and is ordered to. This is part 1 in unlocking classroom activities.
-Laura is struggling emotionally, she'll be casual with sex with Zero but any form of affectation weirds her out and she'll stop talking to Zero for a couple of days. Physical intimacy, like head pats and kisses makes her melt though. The affection bar will be the most important for her. Her activity will be gathering evidence against Xavier for exhibition sex outside, each girl will have more than just a blackmail picture or mind reading him.
-Jean is where addiction comes back in. She'll initially be dismissive of Zero but give him one chance to impress her. Key here is to get her addicted enough then wait a few days for it to wear off where she'll barge into Zero's room and demand dick. This is where the player can either deny her, resulting in submissive path or give it to her, resulting in affection. Her new location is the mall, since she'd probably like shopping there so much. Said mall also has a photo studio Zero can rent out. Lewd photoshoots to start off with but eventually porn tapes sold under the misnomer that the girls are cosplayers and not the real mutant. Zero of course the only male talent.
-Storm is confident in her body to show it off but not publicly enough. So Zero will have to use the facilities unlocked by other girls to encourage Storm to to be the exhibitionist you know she can be. Getting the rules around being naked outside removed, lewd photo shoots to show how good she looks and finally progressively more naked in front of the class.
This can be done supportively through affection or stubbornly through submissiveness. Storm isn't a natural submissive though, she is a proud woman. This is part 2 of unlocking classroom activities. You can schedule with either Emma or Storm a public sex lesson in front of the class with any girl with a high enough exposure stat. Lessons are how you helped them realize how they are, how good they are at sex, etc etc.
-Jubilee starts off as a vampire but as you progress to sex, she takes in other bodily fluids that start weaker than the effectiveness of blood but eventually one nakadashi is worth a week of protection, then two, then three. She starts to crave sex like a succubus. Her facility unlock is a cam studio. From Zero's bedroom, you can tell the girls to cam for a cut of money. They'll be in their bedrooms in the evening, making them easier to find if you want a specific girl for some reason.