Sully killed Jamie in the TV series "Top Boy" primarily because he saw Jamie as a threat and could not trust him. Although Sully never explicitly states his exact motive, there were several key factors leading to the killing:
- Sully had been dealing with trauma, guilt, and PTSD, which made him more volatile and quick to violence. After being rescued and brought back to the top of the gang hierarchy, he was more aggressive and unafraid to pull the trigger.
- Jamie had proven his loyalty to Dushane by killing Kit, who was Sully's best friend. This act made Sully distrust Jamie even more, viewing him as ruthless and dangerous.
- Dushane intended to make Jamie the next Top Boy, using him as part of a "retirement plan" to leave the drug operation. Sully opposed this plan and felt his and Dushane's visions were not aligned.
- Sully was suspicious of Jamie's long-term intentions, especially after learning about Jamie's behind-the-back plans to secure power and might eventually betray both Sully and Dushane.
- Jamie had previously attempted to have Sully killed, so Sully harbored deep mistrust and possibly saw killing Jamie as eliminating a major competition and protecting his own position.
- Sully's shooting of Jamie was cold and final, done in front of Jamie's younger brothers, signaling a brutal end to the threat Jamie posed.
In summary, Sully killed Jamie out of a mix of personal vendetta, mistrust, and a desire to maintain control and power within the gang environment, perceiving Jamie as an untrustworthy competitor who could not be allowed to rise.
