As well as being the title to the headworld Mikail and other characters are in, The Den is also the name of Mikail's nightclub, as well as his base of operations. It's really popular, a mixture of supernatural creatures living incognito and (mostly) unsuspecting humans. A lot of dealings and a good hold on the monster/supernatural community takes place here and it spreads even out of state. So The Den is a hub of sorts. Any business is carried out in the back in Mikail's study/office. The Den is complete with bouncers, “colleagues”, agents, staff, etc. Supernatural folk and human folk alike. Some of the employed humans more aware than others. Mikail directly owns a lot of property and businesses in the area. His people go into city officials and government jobs in the area too. It's pretty deep. Everyone he's associated with within his group he considers family, a strange quirk of his. Ranging from normal humans, gifted humans, and a variety of beings.
The Leon pack (Named Leon after a county they reside in) originates from midwest America where Spencer's father Richard's(now deceased) pack that Spencer visits from time to time. They age slow-ish but not as slow as Spencer does, so they may look older than Spencer but he is in fact older. Sarah, the co-pack leader is Spencer's cousin's daughter.