You need to use favours (until the talk option is gone) and then big favours (again, until the talk option is gone), then you take them somewhere that's likely to help bring out their fetish once you've got an idea of what it is.
To get their love higher (outside of obsessive mental states) you need to use mind control and Suppress Family Ties.
You need to have had Billy speak to them using favours and big favours before doing any of that.
go to renpy / common / 00console and replace: config.console = False on True
Go to college at weekends (College is open at weekends) and search for her at afternoon and evening.
Lower her willpower to 0 then use waking dream (under psychosism) then you can use unzip and start fucking her.
