The whole last season of Castle was terrible. I would have made it a revenge fantasy where Castle and Javi chase down Lanie and Kate's assassins and Kevin has to choose between his loyalty and his duty (to the job and his family). How far will they go? Everything is filmed in hyper speed. Castle gets shot and dies. Kevin shoots Castle's assassin. Javi takes the fall so Kevin can stay 'clean' and then Javi gets a realistic ending. Paid leave.