Here’s a hot take: OurCiel didn’t inherit asthma. Edit 2/23/21: If he did inherit asthma, it was purposefully exacerbated:
And as we all know, OC was extremely sick the next morning and couldn’t go on the boating trip. Honey might have been in the milk, but I’m betting there was something else in the milk. A lot of poisons are sweet, and are only lethal in certain amounts. And then, fast forward to much later in the manga:
Why wouldn’t he be coughing and unspeakably ill in such deplorable, utterly filthy conditions? He’s a sickly child, after all. With an Aunt who is a doctor with the best care he could have had he was often sick at home. After all the abuse he was subjected to, in such a terrible place for MONTHS, we see no coughing? Nothing?
This is the first thing RCiel says to his brother. He scolds him for being outside in the rain and delivers this line. The Theory Is: Real Ciel, was hiding some dark, dark turmoil as a small child. From everyone including even his own family, his twin, and his dear butlers. Likely, he had a very real serious case of munchausen by proxy. Accompanied by other mental illnesses. While RC may or may not be the mastermind behind everything, he had problems, well before he became a bizarre doll. Edit: 2/23/21 - Even if RC was not the entire mastermind behind it all, I think he had his role to play in what happened ultimately to the Phantomhives and the mastermind exploited him. While OC was later shown having asthma attacks, it very well could have been asthma induced by the poisons he was subjected to as a small child, between the ages of five to ten. If he was indeed poisoned for five years, it surely had some permanent effect on his health and lungs– but it would not be as predictable and as simple to treat, as an ordinary case of naturally-inherited asthma. *Edit: Many people are pointing out the circus ark asthma attack, and his diagnosis as “asthma” but remember: This is the 19th century we’re dealing with. Misdiagnosis happens today. If it looked like asthma and his mother had it, there’s no reason for them to call it anything else. Edit: 2/23/21
This is one of the Translation Notes in Chapter 32 of the Circus Ark. Even Yana Toboso Herself pointed out during this time period “Asthma” was the slap-on diagnosis for a lot of illnesses even from the most skilled physicians. I’d like to point out every attack he suffered so far in this story, was triggered by something severe. We have yet to see an unprovoked, completely random, asthma attack. Scarred lungs, and Lung damage is more fickle and harder to predict than run-of-the-mill asthma. Asthma attacks can occur unprovoked and O!Ciel has never had one without a serious irritant present. In the circus ark, it was the cold/wet that aggravated his lungs. He had another attack while a raging fire and smoke was beside him and smoke is harsh. Also, why didn’t the bloody mustard gas in the green witch arc pretty much kill him if it was asthma? His eyes and skin were affected first, not his lungs? On another note, RC was not a stupid child.
Taken from Kuroshitsuji Side story; a story that is considered in direct relation to the circus Ark. We know he was sneaking cough drops, which had medicinal properties/laudanum in them, during the time period. Real!Ciel was taught how to carefully cook (How to use a victorian stove) and how to carefully measure. There isn’t much else needed to know if your intention is to tamper with someone’s food. We KNOW he knows how to use the stove because this same night was the very night he snuck the warmed-milk and honey to his brothers bedroom. We also know that RC was the one who was allowed to carry the meal up to his brother, and was left with his food; unattended. He wouldn’t have done this if he thought he would get caught. And for the record, because this is important: if he was a mentally ill child, that doesn’t make him evil! And I’m not trying to imply that he was/is or label him as such! Merely, that he was sick himself. Finally, as I and others have pointed out: Sebastian the Dog treated OC differently from EVERYONE in his family, Including Rachel– who had the same illness? Yeah, sorry, I don’t buy that! I don’t buy he hated OC for no reason until the last second the dog was alive. I think he was trying to call attention to something and protect him the best way he knew how without hurting RC ; dogs know.
Edit 8/10/18 - I was talking with @mischief-mage - they pointed out that the comfort food that RC gives to OC has ties to fairy tales to being poisonous. -Mushrooms can be poisonous -Poison apples? (In snow white?) There is symbolism here.
And not only that–
If you recall the time OC was sick in the Circus Arc and recovering in the London Town house, Sebastian made OC the exact same comfort foods.
So it was NOT just a coincidence that Sebastian made OC the milk and honey. Sebastian may know these foods bring comfort to OC but how? Edit: 2/23/21 Admittedly I had forgot Sebastian just happened upon the reciepe, but I think he had a lingering instinct that it meant something to O!Ciel. He has RealCiel’s soul inside him, afterally. But if he was able to obtain this information, what else does he know? New Spice to this Theory: Sebastian knows RC was poisoning his Master, and has kept his mouth shut this entire time.
