Let's see * She is aware of the fact that he was willing and even tried to massacre his entire family for his own sake * In 6x04 he channeled Bonnie's magic to give Damon an aneurysm, which causes Bonnie a lot of physical pain. read more
Both have trapped one another in all three Prison Worlds at one point for revenge; Kai stabbed and left Bonnie in the 1994 Prison World after terrorizing her, Bonnie later manipulated Kai into thinking that she was going to forgive him and then trapped him in the 1903 Prison World. read more