Let's discuss some lore about Primate Murder / White Beast of Gaia, also knows in FGO as Fou-kun.
In the most timelines he is Dead Apostle Ancestor known as Primate Murder and got an absolute authority for killing humans. In the FGO timeline he is knows as Fou-kun and is under influence of Merlin, the sage magus from Camelot. Merlin somehow prevented him from turning into a Beast.
Now, in the Solomon it was said that normally Fou would turn into a monster in any human village, since humans are full of envy and he feeds on emotion of envy. However he didn't turn into such monster in Chaldea, even though he also went into Singularities. We have plenty of evil servants in Chaldea, there was a lot of villains in Singularities either, especially Camelot (Gawain and Tristan are notable examples) and he never turned into a Beast.
It's likely assumed that Guda and Romani are good people who don't know about envy, however good people did exists in any human soceity either, so I kinda don't get how does it work. Chaldea also had people like Marisbilly and Lev Flauros, and full of mages from Association, who are pretty evil (see Seraphix). Yet he never transformed into Beast, feeding on that evil. But if just few good selfless people enough to prevent him from becoming a Beast, he should never transform at all.
Also I honestly seem it weird that Nasu decided to bring Primate Murder into modern lore, since he was hideous existence in original Tsukihime. Not he was just an evil monster, whose existence is tied to killed humans, he was also made Altrouge's lover for no reason. You may think that if TOHNO Shiki got Arcueid (and well deserved, he's really cool and I am hyped for Tsukihime Remake), we may at least get Altrouge, since she's only other female TA, but Nasu says no, there is Primate Murder.
Honestly, that cucking out of Altrouge is really weird Nasu's decision, in line with last year's FGO. Where last good servant was Space Ishtar, last good story chapter was HRM, and only good thing about 2021 is Raikou's interlude being translated, so people may finally see depth of her personality (because of multiple specific terms that interlude had no fan translations for years). There is a reason that even independent wikipedias started to call this summer event "a cuck summer"
It makes me very sad as old Tsukihime and Nasu fan. I even donated a 1140$ in one other game to make a reference to one of Dead Apostle Ancestors, just to confirm level of my dedication. And now I am getting cucked out of Dead Apostle Ancestors in FGO. Hinako made to be obsessed with horse, Sion is obsessed with Zepia, Altrouge is guaranteed to be in love with Primate Murder, who is there in Chaldea, ready to cuck us.
I have small hope at least Nasu wouldn't ruin Merem in Tsukihime Remake.
Primate Murder needs to go. I wish that silouette which was shown in Babylonia (the horned horse) is him as Beast in LB6 (going mad after witnessing what had happen to humanity in that Lostbelt and Beryl's atrocities) and we will defeat and kill him.