NOT MINE, but a friend wanted me to post her theory since she doesnt have a tumblr. This theory was made b4 chapter 27, but nothing in there I think disproves it.
SO! In the chapter where Deryn sees Grian in the hospital by breaking in, we see why Grian wanted to become a vigilatie in the first place. In the explation, we see Florenica look at Grian outside the window in a worried manner, almost like she knew him. Although we havent talked about 27 I feel its important to mention that BigB says "You had to escape" to Grian, giving a call back to 22 where we can see him all bloody and brusied.
The theory is that Grian MAY have been in a relastionship with the Waytes, at least in a goodish way beforehand. As you can see the Waytes started worked with the government, so they have to have some hatred against mutants, In the scene, Florenica seems to be panicked looking for something or someone at night. Since we know Grians was apart of the all seeing coven, we can make an inference that the Waytes are at least related to the coven. My friend has the long shot theory that Grian might be genetically related to the Waytes, probally far away as like a cousin twice removed thing but, although its long shot its possible. I AM assuming the All Seeing Coven is a cult, and in most cults at least half of them are related to each other to keep in inside, and not let it seep out. The way Florenica looks like she's worried about Grian looks like she had to have know him on some personal level. This could be why Grian was targeted, as like a punishment because he escaped. (In chapter 27 it also states the coven had an eye on Grian more than Bigb, because some unknown reason, IT COULD BE that Grian was related to a high family in the coven SUCH AS the Waytes.)
NOW this is all far fetched but she wanted me to say it so I did, feel free to pick this apart in the comments. I will ask if she has more parts as my memory is blurry(she told me this like 3 weeks ago idk much) If I do get more info I will repost this w/the edit
(Fyi, I dont not care about the spelling mistakes, I honestly cannot find the motivation to search up the word and rewrite it bc im, dyslexic<3)