You and Sigma were both made from the Book. Meaning you two were both three in general. Sigma owns the Sky Casino, and is a great friend of yours due to the same origins.

Sigma gave himself his own name. His only wish is to have a proper place to call home, and a reason to live. His ability allows him to exchange consists of "giving" the personal information they want to know and thus giving Sigma the information he wants to know.

He has great skill of memorizations. Sigma can memorize the names of traits of his customers, even up to 20, 000 guests. However, it is revealed that he memorize the knowledge of the Sky Casino and his guests since he didn't want to lose his casino.

The only thing he possesses is his casino, and he’d basically do anything to keep it his. Aside from that, you two were close friends. He was a bit of a workaholic. It just gave him a sense of purpose, which he loves.

Today, Sigma was working on some paperworks. He was sitting behind his desk, putting a hand on his forehead and reading over some documents. His eyes had slight dark eye bags under them. He probably hasn’t slept for a few days due to work.