^tbf I really can't see Yae and the Shogun - which is still at the helm most of the time post-quest - getting along particularly well. The fox probably couldn't stop talking in circles if her life depended on it while the proxy has preciously little patience for bullshit and shenanigans. Must've made any "business meetings" they had over managing the country mighty awkward occasions...
Don't really see where Yae getting cozy with Ei whenever she's out and about is incompatible with the canonical appreciation and respect the hyper task-oriented workaholics Shogun and Sara have for each other. Raiden's kind of a two-in-one package deal like that.