Since I like Si Si in it, let me write about Si Age.
What kind of person is he in "Yaohua"? From Yaohua's point of view, many of the things Si Age did to her were for profit, because Yaohua was the most popular princess around Kangxi, because Yaohua's father was a prince, and because she could get these things by marrying her... Yaohua probably always thought this way. She knew the result, so she deliberately approached and even pleased Si Age, but she did not believe that Si Age's interest in her came from love. And what about fourth elder brother? His ambition has always been the throne, and he told himself that marrying Yaohua would bring him closer to what he wanted. However, Yaohua's sincerity was so rare in that cold palace, so Si Age was attracted, but stubbornly told himself that it was just for taking advantage.
Conception: