FYI, Altai's family is excessively rich and probably functions as Yggdmillenia's wallet. I think they started planning for a Holy Grail War as soon as Yggdmillenia got their hands on it. I'm not sure when Octavian started planning the war, but man, them Nergülgiins were ready early.

The smartest thing to do with him is hide him somewhere where Team Red can't find him, and let Hector do his own thing. I don't think Altai will be able to stomach that for more than a day or two though.

Meng Tian would only be able to attend the super secret Yggdmillennia meeting if the Servants were summoned first, or if Octavian summoned his Servant earlier than the rest. I would assume that they had some sort of meeting before the big 100 Mages Battle, but it might be more interesting if the meeting took place after that event? idk

Though Tian is a fake Master, he'll be relatively inconspicuous at first because he has a pretty good facade going (magic amulet and tattooed command spells). He'll probably pretend to be some allied family's homunculus Master to draw less attention, though his mannerisms and un-Caster-like "Servant" are potential causes for suspicion.

If they do rely on Tian as a back-up leader, he is more than capable of keeping people in line if necessary. Just keep in mind that the last time he was given a position of leadership, he did end up working quite a few of his subordinates to death. He's kind of famous for it.

Tentatively, I think Meng Tian would reveal himself as a false Master after Red Berserker kills Meng Wu, but I'm still not 100% sure about that.

Amaury is, in my head, an official part of the Yggdlmillenia family or at least heavily allied, because being part of the group that rejects the magus association would be adequate revenge for his own rejection from the association. What's up in the air is when and how. If he approached them to join, then it would have been after they announced their withdrawal from the Association, and so he'd be a very recent addition. If he was scouted out by someone else, then he could be an older member. Between the two is prefer the later, but either can work.

General Meng Tian Yggdmillenia

Grail War's been planned for at least three years. I'd say even five.

Notan, what say you that he was scouted by Yggdmillennia in preparation for the separation?

I do want a larger Yggdmillennia thread like what the Red faction have going. Wanted a response from Melon and Smite too before progressing further, but this works for now? Yggdmillennia summoned their Servants three days before the war began, so I think this meeting could take place prior to the summonings? Maybe even literally right before they received their catalysts, using that thread to distribute them?

That would be fun, yeah. I like the idea of them meeting up before the Servants are summoned. Athanasios needs a bit of time to be new and confused before he settles in and starts plotting away, and this works great.