Okay, let's look at the three sections available here: Military, Infrastructure, and Diplomacy. All of them are infected with parasites in need of serious destruction. All of them will give us SOME info, but only one will give us the most information. Zheng Fu can get some info, but not completely capture the parasite like us. Cao Chun will completely destroy the parasite and any connected info.
Our main suspects are Meng reactionaries.
These three have plants from before we discovered Still Waters Deepening. Looking at their previous targets, the workers we've saved, and the enforcers Cao Chun stopped during negotiations, the main targets for the saboteurs are the infrastructure and security. Therefore, Astronomer Wu and Xia Lin are the most suspicious members and the most likely people to have good information or plans.
However, I think thoroughly reviewing all the possible choices is best.
ASTRONOMER WU
Astronomer Wu represents Infrastructure. As a Cyan, he can do the most damage in a fight if mind-controlled, but may have the most resistance (as far as resistance from a Sovereign's works go). He has significant information about the observatory, an important bargaining chip for us during the latter sections, probably the cultural section. The lenses for the observatory are expensive, using White-tier materials (ashes from one of Xiagmen's leaves, IIRC) and are extremely easy to mess up.
Knowing it's a bargaining chip for the Reformist section if the Meng, the ones supporting us, sabotage through Wu can also decrease their strength, something the reactionary groups of the Meng want.
Information from him would give us information on possible infrastructure targets or perhaps Still Waters' knowledge of key bargaining chips. It can also narrow down the specific Meng faction since I doubt all Meng reactionaries would be okay with sabotaging the clans' interests as a whole.
I can also see Astronomer Wu's Mind Palace synergise well with Fat Lake since his Way is specifically about looking deeply into an imperturbable surface and finding information hidden behind or beyond it. So, something about how things don't fully vanish into the depths of Lake Hei?
NB: I just realised that the White Sky seeing a Cyan+ sabotage things/get aggressive would also be pretty bad for us, since they're mostly Greens.
XIA LIN
Xia Lin represents the Military. She has significant knowledge of our plans and agendas as one of Renxiang's retainers. She's also our main liaison for the White Plumes, and she's the one who usually catches incidents when we can't. Sabotage from her can include our close plans and other incidents. She's also in Renxiang's main circle, so anything involving her would reflect very badly on us.
Granted, she has some form of protection in Cai gear and in Xia Ren. I doubt Xia Ren won't be able to sense or minimise sabotage her troops since she was a general during the Hui's time. So, I feel like there's limited damage she can do before Xia Ren stops her. But, well, I feel like anything targeting our security force will raise Xia Ren's shackles and mess up our favour with them.
In terms of the information we can gain on the saboteurs, I think we can gain information on their more hidden plans since they tried to hide their attack on the enforcers from Cao Chun.
I assume it'll work similarly for Xia Ren. In terms of cultivation scenes, I'm not sure. Xia Lin has been described as a blade of wind pushing the horizon further back, IIRC.
BAI XIA ANXI
Xia Anxi represents Diplomacy. So far, it doesn't seem like the saboteurs have targeted any diplomats so far. However, based on discussions on the discord with Yrs, it turns out that we would have an additional person to clear if we didn't share information with the White Sky. Seeing as how all the people we have to clear are Named/previously known and how all the White Sky people we know so far are in some way diplomats, diplomats may still be on the table.
Now, Xia Anxi is mainly a diplomat for the Bai. Since we voted for duals to have closed-door discussions, their fights or sabotage won't look bad on us and target our favour if it happens during their diplomacy during recess. However, if it happens outside of that, it can reflect badly on the Empire and thus us. The White Sky already kind sees the Empire as disorganised, and Liling didn't really help us in that regard.
Furthermore, any incident with the Bai can help Liling with whatever she's plotting since she is plotting something. However, apart from making the Empire look bad and potentially causing a scandal, I can't see anything sabotage.
However, the Meng have beef with the Bai, so this might be why they're targeting him. It can mess up the Bai's involvement in the summit, keeping them out of this opportunity. I think the information we can get from the parasite will give the least information since a lot of the Meng dislike/hate the Bai.
In terms of cultivation scenes, though, Anxi's mind palace is probably the best for the summit, as he's a Bai who's experienced Lake Hei and loves fishing there (based on what little we know about him). He's also an astronomer and defends himself by distancing himself from things seen as bad. It works really well for Fat Lake.
Looking at all three, I think Astronomer Wu is the best in terms of information on the saboteur and the potential to mess up future negotiations, which is something we would want since Lign Qi is the only one who can fully preserve the parasites for analysis. The field he represents is also something that the saboteurs have frequently targeted in the past, so the likelihood that the information he gives is important is high.
Plus, it'll be fun if people think we can enter the minds of Cyans with no issue. We could get a +1 to Dreamwalkder!!
However, Anxi is probably the best for cultivation scenes.
[ ] Astronomer Wu