Among other things,
To say nothing of all the h/c one can do with a bed-bound psychically broken Gou Jian.
I have a theory about Fan Li. He has a little motor in his head that turns on when someone presents him with a practical problem, and then it takes over from the other Fan Li automatically. His voice changes, his manners change, he becomes another person. He's done it at least twice in Wu to date. Goes from an oppressed prisoner or the outraged woeful guy facing the man who took his woman from him by force, to the politician or the engineer or the you name it, nattering away pera-pera-pera. Why did he stop giving great advice when he was a prisoner in Wu? The answer's in an edited bit, doubtless. Or possibly it's because Bo Pi didn't sit him down again and specifically *say* OK look I want to do this how do I do it?
The Yue guys are singing Furusato. Really, I can't imagine what else one would sing while a prisoner in a foreign land.
As for the happy times: I'll agree with
Never mind Xi Shi: if Zheng Dan is what passes for second greatest beauty in Yue... er, I can only say de gustibus non disputandum est, and leave it at that.
On the rare occasions when Ya Yu screws up, she screws up majorly. Not referring to Xi Shi here, but to that chilling little moment in 32 when Gou Jian calls to her as she's leaving and hesitantly says (as per the subtitles) 'You wouldn't care to stay...?' and she says 'No, I have to go back to the palace.' Which may not have been a screw-up on her part but something deliberate, which is even more chilling.
Though as for Xi Shi: what I especially like about this series is the iteration of the same theme in different context, best seen obviously in the three versions of the feather recitation. The Fan Li and Xi Shi subplot echoes exactly to my mind WZX's handing over of Ya Yu to the Jin ambassador. Gou Jian let her go, because a show of indifference is necessary to his plan to get them out of Wu. Ya Yu understands that's why it happened and that's why he did it and that it's one of the nasty side-effects of being a helpless conquered people. It hurt enough that she wanted to die, but she's not going to die, then or now, until the king's mission has been accomplished, because there's things more important than her own pain. Like, you know, getting alive out of Wu and making Yue strong again: in pursuit of which goal the king suffered a lot more, physically and psychologically, than she did.
So I can see why Gou Jian is angered that Fan Li isn't able to do what he did, and angered that his wife doesn't get it either the first time (though all of that barking at both of them looked largely like an act for the benefit of Gongsun.) He apologizes to Ya Yu; he apologizes to Fan Li: and that's why he's not, as he says, the Gou Jian he used to be. I like him for it but I'm not quite sure either deserved the apology they got. While of course it was necessary to keep the wa of the royal (extended) family, since the wa of his courtiers seems to be what keeps Gou Jian steady these days. A thirst for revenge will get a man out of prison but you can't run kingdoms on it.
And to date, the action is following exactly what our HK staff said it would: the tyrant who became humane after suffering imprisonment and humiliation.