jekyll would really enjoy the act of slowly finding out what turns on his partner the most, where s/he's most sensitive, learning about that part of them in general
he likes taboo stuff because he is literally the personification of taboo desires. the harder the kink, the more he's into it. BDSM, public humiliation, even violence are on the table for him (though i need a lot of plotting to consider that last one).
there's actually a bit of overlap in that he, too, likes to figure out what his partner likes the most, only he's just as liable to deprive them of it for his enjoyment