Daemon Lords or Daemon Princes, sometimes called The Dark Gods, are powerful malevolent entities hailing from the lower realms of The Astral Warp. Depending on where they are, each circle of hell contains single Daemon Lord that governs over all beings who reside in its assigned circles. They have full reign over the circle their governing in and has powerful reality-warping abilities in which they can easily make and unmake small multiverses within their circle. It is because of their vast power and cruel nature, that all the other circles must remain natural ground or else, the forces of heaven will take the opportunity to attack when full war is broken loose in hell.
While these Daemon Lords appear to be omnipotent and omnipresent in their respective circle, they lose some of their power when manifesting in the physical world like any other daemon, but unlike normal daemon, these daemon lords are able to easily manifest albeit their powers are weakened to degree. The status as Daemon Prince or Lord doesn't last forever, there is hierarchy in hell that lesser and weaker daemons has the opportunity to rise above their ranks and eventually reach to state that they are able to contend and duel the current Daemon Lord over supreme position in their circle.
Just like daemons, the dark gods are cruel and bloodthirsty in their job as they play around with souls, inflicting pain and anguish depending on what circle they embody as. Even then, some of them can be reasoned through deal or contract of some kind but most of the time, these involved in selling their soul and ripping the deal off as they are able to be manipulative and cunning like the rest of the daemon's kin.
As one of the most powerful daemon after gaining their status, many would assume that their power is unmatched in hell but in truth, even if they reach that level of power, they all must obey the laws and commands of Satan or sometimes referred to be the crawling chaos, Nyarlathotep himself.
No matter what daemon or status they achieve, none of them are considered less than a servant to Nyarlathotep since it would mean lack of importance to him while others claim themselves equal to the being himself yet their power are not matched by his own power. It is because of him, most daemons in hell are fearful and subject to do anything he commanded or else, he would destroy them outright.