First with the Lauryn business. She's still alive because she's Jaq's sister and I feel at least Sully has a soft spot for Jaq. When Curtis went after Dushane's family her life was hanging by a thread though, with Jaq saying she'd be done with her for good after killing Curtis. It would've left Lauryn alone in the world and she can't cope without her sister so she took it upon herself to kill Curtis. That regained her the sympathy of her sister and maybe even Sully.
With regards to Jamie. Sully and Dushane both have blinders for different things. Sully values family above all and sees Jamie as a clear threat to that, a threat that isn't going to go away if you don't make it. Dushane is after money and reputation and Jamie was useful in pursuit of that so he wrongly kept him on.
Jamie was always gonna be looking for a chance to usurp him, especially after what Dushane did to Jamie's family and Kit. The final kick in the teeth for Sully was finding out Dushane had been lying again with regards to Lauryn, leading to a further rift between the two. After that Sully did do things his way, which is killing a threat rather than managing it. This has been building up since the beginning of the season and finally came to a head with the latest fallout between Dushane and Sully.
The difference between managing a threat and killing it also showed in how they handled Ruben, which was foreshadowing on how the Jamie situation would be dealt with.
With regards to Jamie. Sully and Dushane both have blinders for different things. Sully values family above all and sees Jamie as a clear threat to that, a threat that isn't going to go away if you don't make it. Dushane is after money and reputation and Jamie was useful in pursuit of that so he wrongly kept him on.
Jamie was always gonna be looking for a chance to usurp him, especially after what Dushane did to Jamie's family and Kit. The final kick in the teeth for Sully was finding out Dushane had been lying again with regards to Lauryn, leading to a further rift between the two. After that Sully did do things his way, which is killing a threat rather than managing it. This has been building up since the beginning of the season and finally came to a head with the latest fallout between Dushane and Sully.
The difference between managing a threat and killing it also showed in how they handled Ruben, which was foreshadowing on how the Jamie situation would be dealt with.