After letting the kids process the news, Logan walks past Tom (Matthew Macfayden) outside and gives him a friendly pat on the shoulder. Shiv sees this happening. It was unprecedented for her father to show affection to Tom, so she put two and two together and discovered that Tom had told Logan about her plans with her brothers.
Earlier in the episode, when Shiv called Tom to tell him that she and her brothers were plotting to overthrow Logan and put herself in WayStar-Royco’s shoes, Shiv made an important mistake: she let Tom out of his plan. It was a quintessential Shiv move that made her husband a latecomer. This time, I thought, Tom used the situation to his advantage.
After a call with Shiv, Tom talks to Greg (Nicholas Braun) at the wedding. He asked him if, after the impending shake-up of the company, Greg would be willing to side with Tom in any of his new roles. He said he needed an attack dog – specifically “Gregweiler”. Tom asks Greg if he’s willing to “deal with the devil,” Greg agrees, and they sign the deal with a handshake.
Looking back, that moment looked a lot more sinister. Tom decided to betray his wife and told Logan about her plan. It’s possible Logan promised Tom some kind of key position at ATN, and when he calls himself “the devil”, it’s not really a joke.
“Succession” spent Season 3 teasing the possibility that someone in the family would switch allegiance and betray others. In the end, it turned out to be most of them. Even Tom Wambsgants got in on the action.
If you or anyone you know has been a victim of sexual assault, be ready to help. Visit Rape, Abuse & Incest National Network Website or contact the RAINN National Helpline at 1-800-656-HOPE (4673).
https://www.looper.com/704934/the-ending-of-succession-season-3-explained/ Explanation of the end of the succession part 3