So I was just thinking, doesn't Lucy still sleep with teddy bears? And didn't she even masturbate with one? I don't know if this was already planned, but I think it would be really neat if her submissive route involved hypnotizing her into thinking of herself like a stuffed animal. The idea of "being a toy" is a classic mind control trope, but it takes on a different meaning to someone who still sleeps with stuffed animals. Instead of being some inanimate plaything, it's a source of love and comfort whose owners often imagine it returning their love, to be cuddled with whenever you want and keep you company while you sleep. And classics like Toy Story and The Teddy Bears' Picnic shows that children like to imagine their toys as having their own lives and not feeling neglected when their owners are away, but still always choose to come home to be loved and played with. Even if the teddy bear goes off to have a picnic with his friends while you're away, you can always count on him being on your bed waiting for you when you come back, because he loves you more than anything. Hypnotically walking Lucy through that scenario and having her identify as a cherished toy could be a great way to condition her into submitting to the protagonist.
And then you remind her that she used her teddy bear to get off...
I'm a big fan of "Master", but I'd like to use it even in the love route. "Honey" is just... Eh.