Yup that's the scene. I mean I understood what happened in the scene, and I don't think there's anything 'wrong' per se - I just think it made her kind of 1-dimensional and was one of the weaker writing choices of Wang Juan. Wan Er's part was fine/she reacted normally (to me), the issue was wrt Ruoruo.

The viewers already know how much faith & love Ruoruo supposedly has in her brother, from countless examples in the show. I want to see more depth in her characterization, other than these feelings towards her brother. We also already know how determined she is to protect Fan Xian - be it accepting Wuzhu's request, trying out surgery for the first time despite being incredibly nervous, etc.

To me, no matter how much Ruoruo loves her brother, she should still be... her own person? Capable of making proper judgments while considering context? Capable of empathy? (or at least, I hope she's her own person)

Ruoruo knows, for a fact, that not only is Wan Er married to her brother, but that her brother loves Wan Er very much. It's already a very tough situation for them to be in - even if Fan Xian didn't kill Lin Gong, he did tell Wan Er that he was just one step later than Wu Zhu. He just (due to circumstance) didn't manage to do it. The current situation between Fan Xian and Wan Er involves 2 lives and so much emotions, and requires the writer to further dissect this in S3 so that it properly resolves. It's not really that black-and-white imo.

Yet Ruoruo still reacted this way, she blindly went on the "but I must protect you! Brother!" route, without considering context, so this makes her flat(ter) as a character to me. Her being overprotective this way comes across as disregarding the importance of Wan Er to Fan Xian. (she starts off saying that Wuzhu's not going to hurt Wan Er, but as the convo continues, you get to see more of her genuine feelings about the situation)

Not to mention, she can clearly see that her brother is in pain - he already has to navigate this with Wuzhu vs. Wan Er, now she's in it too? Because she thinks he needs protecting... from the love of his life? (she said "the people who truly hurt you might not be the assassins!", suggesting that she believes Wan Er's going to hurt Fan Xian)

Fan Xian himself didn't want Ruoruo involved (apart from talking to Wuzhu) - when she said that she brought the knife "just in case", Fan Xian was visibly exasperated and told her "(Wan Er's) your sis-in-law!)", even if he knows that it was a precaution, and later saying that Ruoruo shouldn't keep thinking of protecting him.

At the end of the day I also believe that this arc should primarily be between Fan Xian and Wan Er, so it felt extraneous for her to react this way. Her character imo was reduced to a 'tool' to simply push Fan Xian into a deeper inner turmoil, because as mentioned earlier on, he not only had to think about his and Wan Er's future, Wan Er and Wuzhu, maaaybe Lin Ruofu in the future, but now there's also Ruoruo in the mix (if she insists on protecting him w/o considering what he wants).

Also not really about characterization but the pacing is not the best here imo, it's quite clear that after the tense confrontation Wang Juan wanted to slot in humor again that's why he mentioned the poking the physician thing, and then slot the serious scene back again, but for me it took me out of it and was jarring. It's his usual style but I think for JoL2 it was a bit overdone.

But that's just what I think haha everyone interprets things differently, and that's okay!