#because i think that'll be a treasure trove of examples

[mxtxfanatic]

This is a little random, but during the Nie Mingjue flashbacks, when this part happened:

He knew of people’s likes and dislikes so that he could find suitable solutions; he loved running errands and could do twice the work with half the effort. Thus, Jin GuangYao could be said to be quite a talent at analyzing others’ interests. Nie MingJue was the only person whom Jin GuangYao couldn’t probe out any useful information about.

—Chapt. 49: Guile, exr

...it got me thinking of about what interests he could have possibly found of Lan Xichen’s to exploit. But now that I’ve read a few interactions between Jin Guangyao and Lan Xichen, I think what Jin Guangyao exploits is Lan Xichen’s wish to be a good person without having to face any hard decisions and run the risk of being wrong. He is negatively motivated by guilt.

During the time when Nie Mingjue was still alive but after his feelings towards Jin Guangyao had soured, Jin Guangyao spent a lot of time discussing his issues with Lan Xichen in a way he didn’t do with Nie Mingjue even when their relationship was good. He confides in Lan Xichen about his struggles in Koi Tower, his plans for the lookout towers, and Nie Mingjue’s violent hatred of him. (And some of these complaints feel like they are presented in much the same way Nie Huaisang asks for help of Lan Xichen and Jin Guangyao in his good-for-nothing act!) But Jin Guangyao never asks for anything too strenuous of Lan Xichen, nothing that would put him in a hard place.

When the Jin contingent turn their ire towards Jin Guangyao, he doesn’t ask Lan Xichen for help or to intercede on his behalf. He only asks that Lan Xichen help him expand the hunting grounds “if it won’t bother him.” He doesn’t seem to ask Lan Xichen to argue in support of the lookout towers for him, only to support him as he makes the leap. He asks that Lan Xichen appeal to Nie Mingjue on his behalf, but Lan Xichen was already doing that. Jin Guangyao keeps Lan Xichen around as background support for his different machinations, which allows him to keep his long-suffering but persistent hero persona while making Lan Xichen feel like he has made a difference by being the shoulder the other man cries on. Nothing materially changes for Jin Guangyao with Lan Xichen’s actions.

However, the moment Lan Xichen begins to doubt Jin Guangyao, such as in the Koi Tower discussion conference when Wei Wuxian discovers Nie Mingjue’s head, Jin Guangyao flips to guilting Lan Xichen. Now, Lan Xichen is no longer Jin Guangyao’s only support in the face of adversity; he is just another man in a long list of people who have forsaken poor, downtrodden Meng Yao for his shameful background. When everyone busts in the Jin treasury room and Wei Wuxian accuses him of harboring Nie Mingjue’s head, Jin Guangyao pivots to Lan Xichen, saying “of course you would assume I was the murderer,” which makes Lan Xichen feel guilty. When definitive proof is found of Jin Guangyao’s involvement in Nie Mingjue’s murder and his jade token is revoked, Jin Guangyao shows up to the Cloud Recesses, personally, to throw it into Lan Xichen’s face that he is abandoning their decades-long friendship for falsehoods (negative motivation) before switching to Lan Xichen’s sense of righteousness, his want to be good (positive motivation) by telling him about the new plans to siege the Burial Mounds again in order to trick him into going back to Koi Tower.

Jin Guangyao dangles this carrot and stick over Lan Xichen head right until his very death.