I feel a little suspicious about Vincent, the illegitimate son of Mike's brother in the movie. He approached Mike and eventually became the godfather. A series of activities are all about revenge and power (taking back from Mike the position that originally belonged to his father, that is, the godfather). After the killer finally shot Mike, the killer was stopped, but Vincent immediately shot the gunman, I guess to silence him (but why did Vincent remind Mike that someone was going to assassinate him tonight and wear bulletproof vests? I don't understand here. When Vincent saw that Mike was heartbroken because of Mary's death, I estimated that his inner thoughts were happy, but he couldn't show it. So Vincent's expression in the movie is stiff (whether he is laughing or crying). For revenge, killing Mike may be just a temporary pleasure, but it is even more painful to let Mike fall into grief and hatred for his wife. Just like Mike ended up alone. Of course, this is just my personal opinion. After all, the godfather trilogy is about feuds within the family.