Type Five, the Investigator or Observer, is placed in the head or thinking triad with Six and Seven, and its core emotional material is therefore fear. Its basic desire is to be capable and competent, its basic fear is of being useless, helpless or overwhelmed by the demands of others. Its passion is avarice, meant not as a desire for money but as a hoarding of the self, of time, energy and information, on the assumption that inner resources are scarce; its virtue is non-attachment. Its wings are Four and Six. Under stress the system places Five at Seven, scattering into distraction; in growth it moves to Eight, becoming decisive and willing to act in the world rather than only to understand it.
In the Hornevian groups, Riso and Hudson's second classification drawn from Karen Horney's three neurotic trends, Five falls among the withdrawn types that move away from others, alongside Four and Nine, since its strategy for handling fear is retreat into observation rather than active engagement. This tracks interpersonal strategy, a distinct axis from the head triad's shared core emotion above, and the two groupings are not interchangeable. Naranjo's instinctual subtypes cross each type with one of three biological drives, self-preservation, social and one-to-one (sexual). For Five these give the self-preservation Castle Defender, who withdraws into a well-stocked, defended home; the social Professor, whose command of a body of knowledge marks belonging within a group; and the one-to-one Secret Agent, whose intimacy is built on shared confidences rather than open display.