The fixed signs—Taurus (fixed earth), Leo (fixed fire), Scorpio (foxed water), and Aquarius (fixed air)—are the power or kundalini signs manifesting as will. The most consistent and persistent quadruplicity, they symbolize "action motivated by principle." They are latent, stable, reserved, planners, and reservoirs of energy. Hard aspects between different fixed signs symbolize lessons we have failed to learn over many lifetimes related to the misuse of our will.

Although the fixed signs are all power signs (and collectively known as the serpent signs of the zodiac), each element in this quadruplicity is distinct. In Taurus, fixed earth, the power is latent and the serpent is coiled up energy. In Leo, fixed fire, the power is active and the serpent is uncoiled, as can be seen in the astrological glyph for Leo; in Scorpio, fixed water, the power has gone into the subconscious and the shadow, and needs to be illuminated and made conscious through self-transformation and self-knowledge ; and in Aquarius, fixed air, the universal serpent of wisdom is reflected in the power of the individual will.

Of the three quadruplicities, difficult aspects in the fixed signs are the hardest to overcome. They symbolize the misuse of self-will, and lessons one has failed to learn over many lifetimes that are deeply ingrained patterns of behavior. Only through self-discipline and a great deal of attention can their energy be constructively channeled. Isabelle Hickey calls the four fixed signs "agents of karma," and labels them "Taurus: to do, Leo: to dare, Scorpio: to be silent, Aquarius: to know." She continues, "The disciple has to build in his nature the qualities of action, courage, silence and knowledge."