[X] [A Familiar Face]
...fuck. It's been a while since the last vote in which I was torn between two points.
Unfortunately, not Rin.
Why? Because we are way too disconnected from her compared to all the canon routes.
Now she has no few reasons to try to really kill Shirou:
Shirou having a power-block of Masters/Servants, Mordred injuring badly Baeber, getting Ayako hurt by involving her into this whole mess.
Rin is a traditional Magus who still struggled with her morals yes, but she wouldn't hesitate to wipe out days of Ayako's memory. And Saber is very driven in her desire to win the Grail.
Now, connecting with our big sister is a big plus. Illya deciding to meet her little bro instead of killing him in the spot show how much just having Medusa Rider around changed her for the better. And certainly the two are in good terms after their conversation back in the castle.
...But I'm voting to meet Ritsuka because I'm extremely curious about "Why" and "How" is she here.
Is she the same girl Shirou saved backed in the dream of Singularity F? If not, how different is she from her FGO self?
Alot of questions about her.
And finally, I think Shirou could ask Sakura to talk with Ayako about the basics of Magecraft, the Moonlit World and the Holy Grail War.
Akayo has known Sakura for many years now, and she cares about her. It will surprise her that Sakura is also a Magus, but with her not being directly connected to past events should help Ayako in listening to her. And Sakura does know how hard and even horrifying the life of a Magus can be.
She can understand Akayo confusion and fears, and help her the same Shirou did with her when his participation was revealed.
Edit: Also, at some point Shirou could ask both Circe and Medea that, when they are not busy, to check Mordred. To see if they can figure through their Magecraft what is "wrong" with Mordred. Can't hurt to try if they can do something with whatever version of Madness Enhancement she has.