I spoiled this before, but a repeat if you don't want to wait:
He's dying from magical curse, the stuffs Lily put into the snacks is actually 'medicine' used to hide magic from detection.
It's used by mages back when they were ostracized by the previous king (yes, that priest's longass rant is actually relevant to the plot)
She's forced into this plan by the real mastermind.
Basically her land needed support from the mastermind, and they used that as bargaining chip to make her do this.
I spoiled this before, but a repeat if you don't want to wait:
He's dying from magical curse, the stuffs Lily put into the snacks is actually 'medicine' used to hide magic from detection.
It's used by mages back when they were ostracized by the previous king (yes, that priest's longass rant is actually relevant to the plot)
i dont mean to be the bearer of somewhat bad news here, but just so your aware, this series was officially licensed for an english release. I worked with someone related to the localization team for it, I dont know if its been offically announced yet, and i dont want to get them in trouble, so i wont go into too much detail, but i can say for sure that ive seen the official translation of up to the end of the first volume at the very least. I dont know when its coming out or anything like that, i just know its being worked on.
figured id give you a heads up as i know a lot of groups like to avoid anything licensed for an english release as it comes with an increased risk of the publisher giving a shit. if you dont care about that, then thank you for your bravery, and thank you for the translation.
I spoiled this before, but a repeat if you don't want to wait:
He's dying from magical curse, the stuffs Lily put into the snacks is actually 'medicine' used to hide magic from detection.
It's used by mages back when they were ostracized by the previous king (yes, that priest's longass rant is actually relevant to the plot)
She's forced into this plan by the real mastermind.
Basically her land needed support from the mastermind, and they used that as bargaining chip to make her do this.
We know that one of his conditions was insomnia, so it is possible that it's a lot less a health condition and possibly giving him food that makes it difficult to properly fall asleep or invigorates him. Medicine in high enough doses can turn to poison.
So possibly he was getting too much caffeine, the food had too much concentration on a specific vitamin, or as you pointed out too much sugar on someone who has a low threshold.
The first one is possible, low sleep helps cause immune deficiency and make one more susceptible to disease, the second and third are also possible since we know eating her sweets is a daily routine for him.
Great, now the rabbit hole. Turn of search tracking while looking this up!
Ethylene glycol causes kidney damage and tastes sweet so can be used as a sweetener. Also known as Antifreeze poisoning as it used to be in antifreeze and the sweetness caused animals to drink it.
Cyanide can cause overall weakness, nausea, and headaches. And adding orange zest would cover up the almond taste.
Lead poisoning can cause insomnia. But you usually get a lot more symptoms along with it...
Mercury can also cause insomnia. It can also cause mood swings. Also apparently called the Mad Hatters disease.
Just a shot in the dark, here, but... It's more likely than not a compound-poison - poison that comes in two separate part that, by themselves, are relatively harmless... but when taken together? They interact in horrible ways.
It's kinda like the antidepressants I'm on. By themselves, they're pretty effective. But taken together, one has a multiplicative effect on the other that's not usually recommended at the dosage I'm on - that being the maximum dose that the FDA will permit. In some people, it could cause seizures and cardiac arrest.
I'm one of those types where it takes the pharmaceutical equivalent of a brick to the face to have any effect on me. I hardly even feel Morphine - I have to tell the nurses in the ER not to waste any on me and just go straight to the Dilaudid. They're skeptical at first, for sure, but then they pull up my records and then they're like, "Holy fucking shit" because I once drove myself to the hospital with a ruptured appendix - over ten miles and I couldn't use the freeway because of construction. In my defense, I had no idea my condition was that bad. If I had known, then I would have called emergency services instead.
EDIT: Oh! @WhimsiCat beat me to the punch with the real answer. Nice catch, there. I would have never thought of something like that.