Excellent posts, all! I don't disagree with any.

Michael certainly didn't start out wanting to be the Don--or even to sit with his family at Connie's wedding, or even to identify with them ("That's my family, Kay, it's not me."). And yes, circumstances had a big part in propelling him into the family business.

But, I don't think he was a reluctant Don. As I posted in another thread: Michael had choices and alternatives at every step of his ascent to the Donship, and he chose the Mafia way. He talked a lot about "responsibility" and "legitimacy," "protecting my family from the horrors of this world." But, he liked the absolute power of being the Don--of having no restraints on eliminating enemies, buying alliances,getting his way by any means, legal or illegal, through the sheer exercise of power. He could only get that by wanting to be the Don, not by wearing the mantle of Donship reluctantly.

In the novel, Vito says, "A man has but one destiny." He was referring to Sonny's desire to be in the family business instead of law school. He might just as well have been referring to Michael's choices.