Sonny had to have things 'his way' too. Evident in the staircase shoutout between him & Tom after Vito comes home from the hospital.

That aside, I do agree that Tom was much closer to Sonny than to Michael. I think until Michael returned from Italy to pretty much run the Family, Tom thought of him as the kid brother who needed looking after (and his future 'discussed' with Vito). He was clearly worried when Michael was about to go off & shoot Solozzo. The tables were a bit turned on Tom when Michael eventually became not only his boss, but The Don. While he got crap from Sonny as well, there was more of a warmth, even equality in their relationship.

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