Search Process: Rather than look up specific symptoms, given the vagarities of the symptoms I need and the flexibility I need to use different poisons, I just looked up the symptom profiles of a number of poisons on Wikipedia and google, reading them all and looking for one that hit. I did some reading, on and off wiki, of all the poisons I mention below. I also googled "Untraceable poison" for suggestions.
So, I have an evil villain whose motif is poison. Her use of poisons will drive the plot in three separate incidents. She was born in the capital but rules a region of the tropical area. She's a noble, so she can get away witih a lot.
The first use of poisons is in the story's past. The villain, middle child of 5 and daughter of the queen, is given care of the Crown Prince, her nephew, when one of his parents dies and the other goes into hiding. Resenting him and wanting to be queen herself someday, she tries to poison him, and is thwarted by the covert efforts of her husbands, relatives, and by the young Prince's own resistance. She needs to have tried a number of times and failed very narrowly on most of them, but for plot reasons I can't have the Prince having any cognitive problems that'd prevent him from being an effective ruler, or any physical problems that would make short bursts of awesome fighting impossible. My ideal symptom set would be bouts of fatigue or dizzyness balanced by relative normality. The closest thing I found was Chronic Beryllium Disease, a sensitivity to Beryillium (a metal; due to his parents being earth and fire mages respectively, he'd be more likely to survive) that causes tuberculosis type symptoms. However, I couldn't discern if this comes in waves or bouts at exposure, or progresses pretty uniformly. I'm going to at least have him have a very mild form, but I need multiple poisons and I need some help with this one if I make it more severe. What's the prognosis for someone with moderate disease? Do they have accute allergic reations to new exposure? Does the fatigue and stuff get better or worse? The Prince is in his early 30s now; with moderate disease would he last another ten or so years?
And after that, are there any more poisons that would leave little trace, be mistaken for something else, cause little long term-cognitive damage in children, and would cause the prince to have bouts of fatigue or weakness in which he'd be bedridden but not unconcious?
That's the big doozy. The other two questions are a bit less important or less urgent.
My villain is going to try to goad the prince into being stripped of his birthright by attacking her unprovoked and being stopped by his cousin--the Queen is obsessed with justice, to the point where she paronded the murderer of one of her own children. To do this, Villain princess is going to try to kill the crown prince's mother, an earth mage, who is in hiding. She's going to have an assassin shoot the mother with a poisoned arrow during a storm, when she's not likely to be discovered by any of her body guards. However, the mother's assistant will find her and needs to be able to treat her and ensure her survival with basic first aid. The main thing here is that the poison must not cause lasting damage and must be nearly untraceable, and must be easily survivable with basic treatment, which the mother will get. Bonus points if it's something that is easy to mistake for something else and treat in a way that'll just hasten death, so I can use it for the villain's first husband too. Also bonus points if it causes a fever; the villain and crown prince both are fire mages. I'm having trouble with this because most of the untraceable poisons I know of are untraceable by modern science, but elemental magic based detection will be a bit more sophisticated, and most of the stuff that isn't traceable doesn't seem like something you could dip an arrow in. Arsenic is too obvious and too messy. At the moment I'm favoring milk sickness/tremetol poisoning; the target has a noted fondness for drinking milk, and if the poisoning is light enough it might not be all that messy. I hope. A big strike against this is that it'd be adminsitered by poison arrow, not ingestied (would it still work) and that the prince's mother is the progressive noble in charge of the desert duchy, so it might be hard to establish it as accidental. Still, the prevalence of milk is secured in the setting by a trade network and some enterprising water mages who specialize in ice. Do does that work, or do I need something else?
The last thing is, to take suspicion off herself, the villianous princess is going to poison either herself or her teenage daughter. It must be traceable, but it must not cause permanent damage if treated, and it must be controllable, so neither ends up dying. I seem to have a cognitive block on working with this one; I'm so sensitive to this sort of thing, due to some stuff I was exposed to accidentally as a baby, that I cannot get into the head of a character running the odds of risk of dying versus effective dosage for show in terms of poisoning. I've become horrendously ill from medicines that were supposed to HELP so many times that I can't understand wilingly sickening oneself. So I'm just totally blanking. She needs something with demonstrable symptoms that probably won't kill her, but could have--would have--if some circumstance had been different, a circumstance she could control. Bonus points if it's something that won't be mistaken for a tropical illness, since the villain's palace is subtropical, but that could have been if not for one small detail.
I apologize for asking such broad queries, but I've read so much that I literally can't keep it all straight, and I need to make sure to use three (or four) separate poisons so my villain doesn't look like a chump.