Wren has special interests and they are "murder" and "poison"

this is not a case of "oooh I love to murder people, it's sooo fun!" (as likely implied by earlier writing) so much as she's someone who muses on these topics to the point that she sees totally unrelated (to other people's eyes) concepts through their framing. everything can be poison: not just chemicals, but emotions, environments, concepts, selves. everything can be killed, to some degree or another, leaving an absence that the world must mold itself around.

and in the Neath, where the laws are looser and the immaterial can be made material, this way of thinking isn't just philosophical

the hilarious thing about Spouse(less) Saga is that I do have an alt who I intended to marry off: Wren.

and then she was like "actually, I fell in love with someone once and I absolutely hated it. it made me sick and stupid. it was like being poisoned. if I ever fell in love again I would simply kill the part of me responsible for it"

and I was like, shit. okay. what a statement to make in Fallen London but I respect it

the doctor, as a highly competent (despite all appearances) Correspondent with a very deep understanding of the Red Science, does get inquiries for work, but he's choosy about which projects he takes on given that he much prefers to be doing dubious research or sewing up the newly-dead. that, and he's visibly insane and disreputable even for a Correspondent, and he lives out in a monster-ridden marsh, so most folks end up commissioning someone else.

that being said, he is known to the zailors of London for the tools he makes for them. spyglasses that can see through fog. filters that render zeewater (mostly) drinkable. compasses that always point towards London. simple devices, but all the more sturdy for their simplicity, and invaluable in the hands of a competent zeefarer.

(after all, the doctor first created them as gifts for Rafael: to keep him safe on his travels, and to help him find his way home.)

the doctor's familiarity level with each of the Calendar Council, minimal spoilers version