Another Greek WI, this one might become a short TL if I can butterfly enough interesting stuff out of it.
When Andreas Papandreou originally went back to Greece, it was as a sabbatical from his teaching post at University of Minnesota. He'd been called to establish an economic think-tank in Athens and he served in this capacity for five years before renouncing his American citizenship to run in the Greek parliament in 1964. Of course, IOTL he ends up becoming a vary polarizing and very popular figure, both before and after the dictatorship. However, in his own memoir he concedes that Greek politics didn't initially draw him in, and that his father was the catalyst to his entry into the political arena.
So, what if Andreas Papandreou sticks to his initial assessment of Greek politics as tribal, backward and undignified, and turns down his father's offer of being his economic advisor, which IOTL led to his entry into politics? Given what Andreas got mixed up in or slandered with before the dictatorship (repeated accusations of favoritism from all sides, allegations of quasi-communist conspiring in the Aspida Affair, etc) and the influences he had after (founding PASOK, liberalizing a lot of residual Greek policies from the 50s) I feel like removing him could send butterflies scattering in any direction.