There really is nothing but a scrap of what is known about Van Cleef. He is first mentioned in Obsidian Butterfly when Anita and Edward are taken prisoner by Riker and his men. One of the men, Simon, tells Edward that a man named Van Cleef recognized Edward's picture. Simon then announces to everyone, "Boys, this is the Undertaker, the man that still has the highest body count of anyone Van Cleef ever trained." This seems to unnerve the other men, and it completely baffles Anita. According to Simon, Van Cleef once told him that Edward was dangerous.

At the end of the book, Anita tries to get Edward to talk about Van Cleef, but he refuses, telling her it is better not to know. He says in order to leave, he had to agree not to talk about Van Cleef, otherwise he'll be hunted down. He then adds, in a somewhat sad voice, that this is one secret he does not like keeping.

All that is known now is that Van Cleef is a key figure in Edward's past; the person who obviously taught Edward how to be as good as he is at what he does. Perhaps meeting Van Cleef had changed Edward, because throughout the book Anita sees hints of what could have been a kinder, gentler Edward.