In a way, The Ouroboros Cycle is about like the whole concept of seeking to destroy the Foundation and then becoming an Overseer, but I’ve always kind of personally seen it more as a never ending cycle of betrayal between specifically O5-1s and Engineers
The first being Aaron Siegel, who was also once an engineer, and Vincent Arians/Anthony Wright. I believe it was Vince that wrote the operandi calling for the overseers deaths and then they were followed by yet again, another pair of chaos insurgents who sought to destroy the Foundation, and one became engineer and the other O5-1
Adam & Vincent’s parallels mean so much to me especially given the fact that Vincent rescued Adam when he was a child. Then Calvin and Aaron have their issues that can never be addressed sigh
The engineer/O5-1 being doomed ships is also part of the cycle. If Adam loved Calvin there’s nothing saying Vincent didn’t love Aaron