Kai was a vicious sociopath and the biggest piece of work The Vampire Diaries has seen for a long time, so why has the character garnered such a huge following within the fandom?
Although nobody in their right mind could support Kai's brutal murder of Jo and her unborn children, his erratic actions and twisted sense of humor made him a compelling character to watch and one that is reminiscent of a couple of beloved villains.
As Reddit user Orctus points out, there is more than a little of Batman's Joker about Kai and maybe it is his playful yet sinister nature than fans have found so compelling.
Although the season 6 villain's brand of evil is a lot more goal driven than the iconic DC villain, his playful toying with Damon and Bonnie in the prison world along with his witty one liners are definitely reminiscent of the comic book character.
Personally, I think Kai is more like an early Damon with even less of a conscience and that's probably why I warmed to the villain so much.
That and the fact that he was genuinely unpredictable, suitable cutthroat and drop dead gorgeous. Although I'll miss him, I'm still glad he went out like this though!