Open to your own interpretation but i have an idea flouting around on KP arriving on a "cursed" island that haunts people with the ghosts of those the regret loosing.
Killer and Kidd are prepared to see Victoria. Instead they are met with the shadows of those they never had a chance to mourn for. For killer, its the little sister he lost in childhood. It wasn't his fault, he was only four when she disappeared. But the last thing he was told was to watch out for her.
Can he forgive himelf, and let the child go? Or is he dooming himself by holding on to the past and trying to save someone who's already lost?