Thanks for the feedback! The Brian scenes in both 37 and 38 were so much fun to write! After basically writing a whole story in which the characters are lying in hospital beds, it was nice to finally be able to include some action.
Yeah, they were both fine before the freak squad got their hands on them. They used a neuromuscular blocking agent on Brian to paralyze him - same kind of drug that's used for general anesthesia, but without the sedatives and painkillers that put you to sleep and numb you up.
As for Nick, they flat out lied to him about a lot of things, but his physical symptoms were side effects of digoxin poisoning. When I first came up with this idea, I was going to use potassium because I knew too much or too little potassium will mess with your heart and can cause cardiac arrest in extreme cases, but once I started researching, I read that it burns when injected in the kind of doses they would need to trigger those kind of side effects, so that would be too obvious. Then I started looking into healthcare serial workers to see what other drugs one could get away with using without being obvious, and I discovered Charles Cullen, who was a nurse in New Jersey who killed a bunch of patients with digoxin. I read a whole book about him. Anyway, digoxin is the perfect drug for this because it's used to treat heart failure, arrhythmias, etc., but it can easily build to toxic levels and cause a lot of heart-related side effects that are similar to the symptoms of the conditions it's used to treat. So nothing was really wrong with Nick in the beginning, but he is legitimately sick now because of everything they've done to him, including implant that thing in him with materials that may not have been sterilized to hospital standards.