The first trait came from the Incubus's own bloodline characteristics.
The second trait was derived from the skills recorded in the bloodline after extracting others and toying with people's hearts and bodies.
The third and fourth traits came from the demon race itself.
Obviously, before Kael merged with his original self, the first supernatural trait chosen by the original self was charm.
If Kael continuously enhanced his own bloodline abilities, under normal circumstances, he would undergo another bloodline evolution between LV7 and LV10.
If he chose "charm" again for this bloodline evolution, his profession core would effectively integrate one low-level charm (originating from his original self's first appointment as a magician) and one high-level charm (originating from Kael's complete awakening of the incubus bloodline).
