Mythic Origins

All major Mesoamerican civilizations (Mayans, Aztec, Inca, etc) prominently held a jaguar in their pantheon, and for many this revered predator played an important role in their religious rituals and shamanistic magics.
Shamans viewed the Jaguar as a spirit companion, or nagual that protected them while they moved between the earth and the spirit realm. In order for the shamans to combat whatever evil forces may have threatened, or for those who relied on the shamans for protection, it was necessary for the shamans to transform and cross over to the spirit realm. The jaguar was often seen as a nagual because of its strength, for it was necessary that the shamans "dominate the spirits, in the same way as a predator dominates its prey".
Leadership & Social Structure
Jaguars are the most solitary of the big cat lycanthropes, following the rule of the jungle in which the strong survive and the weak perish. Each Jaguar rules their own turf, gaining or losing ground by their own skill. Male jaguars do not mind sharing their territory with female jaguars, but when another male encroaches, he is met with fearsome resistance.
While they will socialize and seek out mates, they almost never allow these bonds to confine or constrain them. Even the females in a male's territory are used for pleasure and procreation rather than for forming tight family bonds. Female jaguars are no less formidable than males, but still benefit from the primitive patriarchy. Jaguars do not rely on others to do what they can do for themselves, but are surprisingly willing to take on the role of protector when it suits them.
General Traits & Abilities

Werejaguars have an innate instinct for inflicting pain, using their massive paws to hold tight and claws to rip and tear into their prey. They excel at stalking, distracting their targets in order to gain a positioning advantage, and can employ some magics to shroud themselves and further aid the concealment of their movements or escape.
Because of their solitary nature and mentality for self-sufficiency, other beings will find it extremely difficult to use psychic abilities and mental powers on.
"Do they send all of you jaguars through some elitist asshole training course?"~Lisa Kessler (Wolf Moon (Moon, #7))