Darkness.

Ace Alessio Adrin and Arabelle Salvatore. They brothers rule the underworld and is known as the "Murderous Three" but each of them have there own title. Ace is know as "Satanic King" Alessio is known as "Darker ghost" Adrin is known as "Blood Drop" and Arabelle is known as "Lucifer's Queen" each of them maintain a title in the world. Illegal and legal. Each of them has there own marks. Ace's mark is finding the victims heart in your bed. He rips them out with his bare hands. Alessio leave a message for the family. "I will see you tonight" and like message says. They can run but he will always find them. Adrin mark is a simbol. A laughing skull, dripping with blood. Says if you look at it, it will haunt you forever. And it's true people have gone crazy because of it. And Arabelle leave a picture. Of you walking into your house, a couple of seconds ago. And then the picture turns black all your lights go off and when they go back on your entire room is cover in blood. And a creepy voice saying "I be back" with a sweet giggle afterwards.

Safe to say they're mental. But there broken each in there own unique way.