(fallen london stamps by there's this time when Wren, Nathan, and the doctor are eating together somewhere, and she notices that the doctor is unusually quiet. so she looks over and sees him staring at his plate. there's smoke starting to come out of his nose and mouth.
so she grabs her water glass and SPLASHES HIM IN THE FACE and when he's sputtering she's like, how many times have I told you! stop thinking about the Red Science at the dinner table! and he's like, but I'm sooo close to figuring out this-- and then he begins coughing up great gouts of smoke and his hair bursts into flame. so she grabs his water glass and upends it over him, while being like CORRESPONDENTS. WHY ARE YOU LIKE THIS. (and then she's like, no offense, Nathan.)
there has also been at least one occasion where the doctor was hecking dying on her floor after trying one of her poisons. and she's like, okay, I've seen enough, and administers the antidote. and when he recovers he's like AW I WOULD HAVE GOTTEN IT IF I'D JUST HAD A LITTLE MORE TIME. and she's like, sure, buddy. here's a washcloth to wipe the drool off of your face.
they have some kind of friendship, that's for sure
additional fact: the doctor did some surgeries for her, but she brews her own HRT