The dialogue in this section is SO distinct for each character it's almost unfair. Let me just lay out why this works so well.
The Emperor—his voice is lazy, dismissive, almost bored. "Enough. Young Master Song, you must live well with Zhaoying from now on. I am tired. All of you may withdraw." He's thinking about summoning new beauties and these political marriages are just background noise to him. The casual cruelty of a man who holds everyone's fate in his hands and can't be bothered to care.
Madam Song and Song Chengyu—scheming, sharp, desperate. "Your Majesty, you once said that when Chengyu marries, you would allow him to inherit the marquisate." They're calculating every word, every bow, every display of "maidenly charm." Their dialogue is transactional, which makes perfect sense because that's exactly what their relationship with Jiang Zhaoying is.
Wei Jiuzhao—warm, concerned, slightly formal. "Ying'er, firstly, you must be careful, and secondly, if anything happens, you must tell us." The double bullet point structure of his care is so endearing. He's their senior brother but he speaks like a worried parent.
Xu Zhiyan—quiet, restrained, but when he speaks it cuts. "No matter what method is used, you must secure a divorce!" One line and you feel the desperation underneath.
And the Crown Prince—each word is measured, cold, razor-sharp. "If you are wrong, what then?" "But what if I still do not believe you?" He doesn't raise his voice once. He doesn't need to.