I'm really confused that the end clips show Zhang San's diary .. is it Xiahou Dan when he was young or is it the…
Yes same actor but different roles. Zhang San is Xia Hou Dan's original name, before he transmigrated into the novel. These ending parts basically show his memories from then. So it was him that killed the maid
That moment while examining the SOS flowers and Yu Wanyin asked the young Crown Prince questions to see if he…
the crown prince is not the emperor. they are just played by the same actor. The kid is Xiahou Dan's son after the empress dowager forced him to have a baby with a consort.
My only question is, why did the ML actually transmigrated 15 years ago and how was he stucked in the novel for…
It is somehow explained later, but not clearly. For Xiahou Dan, Wanyin was like a savior who would help him survive in the palace against the empress and Prince Duan. He went through a lot of stuff after he transmigrated, and he felt all alone. So when Wanyin came and was like "how are you," it was like he finally found someone like him