Joshua created this particular Rote through personal experience. Back when Morgan was still an Archon, her Blood Bond to her Justicar superior was his first target. The concept of the Blood Bond, both its physical and psychological aspects, had already been explained to him in detail. Now, of course, he has his own Bond with Morgan as a sort of reference. While he refers to this Rote in much simpler terms, such as "scanning for traces of the Vaulderie," the name above was used when he submitted it to his peers, although that time seems so long ago to him now.The Blood Bond leaves signs of its presence in the Pattern of a being, whether living or undead. Joshua's familiarity with those Pattern-traces allows him to deduce when such a Blood Bond, even in part, is present in a being. Joshua knows the difference between a normal Blood Bond and what he refers to as the "Sabbat variation," Vinculum bonds. This knowledge arms him with a reliable means to identify Sabbat. Faces are mutable, given the use of Obfuscate and Vicissitude, auras can be faked with sufficient power, and Cainites may of course lie freely regarding their lineage and sect allegiance...but the Ties of Blood will tell.