(Disclaimer: haven't played the game in a long while, not since the BE update.)
Idea:
She gets transformation powers added to her list of abilities. Obviously she can't ACTUALLY transform you, but it just adjusts the different challenges and tweaks some dialogue and camera angles.
Examples of TF'ing you:
-Turning you into a cow, referring to you as a cow, commanding you to moo, giving you challenges that are more nipple/boob/chest focused.
-Turning you into other animals too, I guess, however they'd individually work, IDK.
-Shrinking you, lowering the camera angle by a lot, doing more challenges like being sat on or stepped on, holding you in her hand, pretending she's going to eat you (or maybe she actually will? I don't know if that fits the game's theme much though. Swallow you, then give you commands in the dark?)
-Turning you into a null, shutting off all genital-related commands; mechanically, it functions like a renamed chastity toggle.
-[THING] removal, like removing your arms so you can't do challenges that involve your hands, making you have to use... alternate methods
Examples of her TF'ing herself: (These take a lot more work since they'd need to be modeled and/or animated.)
-More expansion/loss stuff, like if you like butts and you make her mad, she'll shrink her butt flat, or if you're doing good and you like thighs, she'll make her thighs bigger.
-Dick growth, (requires player insertion to be enabled), she'll do a ton more insertion challenges, and they could be harder too, I guess. (Also a dick removal one too, in case she already has a dick.)
-Animal TF, lots of animal ears and whatnot, also changing her dialogue, and making some challenges a bit different, or even new challenges like she turns herself into a cow and you have to chug a quart of milk as she forcefully breastfeeds you.
-Roid rage: she gains some muscle mass; challenges get harder and she's more irritable.
-Making herself invisible to punish you, so you lose the eye candy aspect of the game