As the legitimate son, he was constantly taking medicine, yet exceptionally clever. Within a few years, he lost his older brother and his mother, and several times he came back from the brink of death. Kangxi repeatedly lamented that if his legitimate son were healthy, the crown prince's position would undoubtedly be his.
1. This is an alternate-history Qing Dynasty story. I've only done some cursory research, so please go easy on historical accuracy enthusiasts.
2. The protagonist is Cheng Ku's twin younger brother and the same-mother elder brother of Crown Prince Yinreng. He is a person who never existed in history.
3. The idea came from the First Prince's resentment: he was the eldest son born to a concubine, while the Crown Prince was the legitimate son.
Any word next to the sight word is better than "you". Kangxi's son's preface to "teeth" is all next to the sight word, and the protagonist has not started to preface "teeth" when he was born. After the historical Yinyou is born, you can also find another word next to the sight word. Why use "you"?