In S12E3, when the Dregs (giant mutated killing machines) take Benni, they carry him with them and leave him alive a long time, long enough to say his farewells to his partner when the Dregs are outside the vehicle (which the Dregs let him do). This must be at least 20 minutes later.
This is contrary to their modus operandi with other people, which is to kill them as fast as possible, as we saw with the other guests and resort employees. The only other exception is when the Doctor threatens the head Dreg into letting them walk out. One character speculates that the Dregs want to toy with him, but that seems unconvincing given their lack of interest in doing so either before or after.
So why did they keep him alive so long?