Grimlord evidently first gained his powers from an ancient Egyptian artifact called the Box of Isis. Bansheera and her demons were sealed in Egypt...
It's an open relationship so they're perfectly okay with pursuing romances outside their group and it's mainly for emotional support besides the sexual benefits, not to mention Ryan and J.B. would be stigmatized for sleeping with each other in the early nineties or even today. Kaitlin is more focused on her career at this point and (onscreen) has the least interest in dating of the three and uses their FWB situation to keep from focusing on a relationship that would distract from her job. No one else really knows though Tao suspects what they're doing, but also respects their privacy enough to leave them alone. They're basically a three-way Battle Couple. They also have a promise that one of the guys will marry Kaitlin if they're still single by the time they hit a certain age with the "third wheel" being their close friend that just so happens to rent a room in their home (it's pretty much unspoken between the three that J.B and Kaitlin are the marrying couple if that occurs.)
