This was the clue that made me realize everything:
D = Earth
C = Fire
N = Water
H = Air
Now, it works this way:
D: Duality with N. Conflictor with H. Supervisee and Benefactor to C.
C: Duality with H. Conflictor with N. Supervisor and Beneficiary to D.
N: Duality with D. Conflictor with C. Supervisee and Benefactor to H.
H: Duality with C. Conflictor with D. Supervisor and Beneficiary to N.
Air and Fire have no Supervisors (controller). Air and fire cannot be controlled.
Water and Earth have no Benefactors (requester). Water and Earth cannot be demanded from.
Tell me what do you think.