AngryFrozenWater wrote...
I think it is clear from the animations and images in the epilogue that the glowing green eyes and patterns are seen on reapers, husks, synthetics and organics. There is no indication that there are exceptions. And we know that the essence of who Shepard is and what Shepard is has been added to the mix. That has implications for free will.
That brings us back on topic. If it exists then so will the reapers' purpose and aggression exist. And because of that, the inevitable synthetics threat will force the reapers to search for other galaxies in which they can violate the right of self-determination once more. If that threat is inevitable then this will be true in other galaxies as well. There is no reason to assume the threat is a local problem. And thus it will not take long before synthetics from other galaxies arrive here to attack us! So the reapers must strike first to once more save us all by performing their legendary genocides and other atrocities in the rest of the universe. After all, it is inevitable!
That inevitability has led the synthesis fans to their choice. And they think it was right. So according to them the above scenario must be true. If synthesis somehow prevents this then 1) the threat was never inevitable or 2) mind control does exist.
One plus three does not equal two. Sometimes glowing green eyes just means their eyes changed.

There is nothing inevitable about the scenario you provide because it relies upon too many assumptions. The most obvious one being that life in other galaxies exists and will take the same path as life in this one. Secondly that the Reapers are following the same programming. Which, following Synthesis, they are not.
What they get from synthesis is essentially a 'soul.' And that gives them an appreciation and respect for organic life they did not previously have. Is that mind control, or simply an expanded perspective that they did not have before? Either way its nothing is 'inevitable' because entirely new data has been added to the equation.
It was a frequent theme in talks with Legion that changes in available information leads to a different consensus. Which brings me back to the question I posed on the previous page. Upgrading the Geth brought them closer to having free will, not taking it away from them. By all evidence it did the exact opposite of what you assume Synthesis will do, even though by all dialogue given, Synthesis is the next step down that same road.