The Beta Clan is full of shady characters most of which are mechademons, an invention of Dr. Mihos, or "half-bloods" or people who are half hellion and half mortal.
Dr. Mihos is called the "Doctor of Demons" because he invented creatures called mechademons. They are a combination of a mechanical bone structure and organic flesh. He is also known to be able to replicate the look of other mortals with clones.
All the research of Dr. Mihos stemmed from projects he worked on when he worked with the Dionne Military. He created many mechademons and experimented on a few hybrids. A hybrid is a combination of hellion, mortal and angel and are extrememly powerful if their power can be unlocked. He also used many of the clan leader's children for experiments. More is revealed in Volume 5.
Sakumo is proclaimed as the guardian of the Beta Clan, but in truth, they have rebelled so far away from Uni and Tin's laws that they are no longer considered protectable. There are regular mortals in the Beta Clan such as Uranus's mother who is a full blood mortal. Uranus, himself, is a half-blood which is a half-mortal and half hellion. Sakumo used to the be the guardian angel of Dr. Mihos, but when he turned evil she became the guardian of Aysa, his daughter, instead.