I've known some Greek Orthodox and I wasn't impressed. I think they're annoying. "Theosis" and "divine energies" for them and their belly buttons but no to the Filioque, etc. When the Turks were getting closer to their objectives in Constantinople, the Greeks didn't want any help from the West, and they would say "the turban before the mitre". And that's what they've gotten since 1453.
The Holy Spirit proceeds from the Father, of course, and to the Son, but what then? His whole procession business just freezes up when it comes to God the Son? He proceeds from the Father to the Son and then the freezing process begins abruptly because he doesn't do anything at all after that. Or at least the Greeks insist that he should not. And where the Holy Spirt freezes up like that, that's where the Greeks see their chance, and want to take over. But then fate has the Turks come in and there you go.