The Dark Lords are characters in the Souls series.
"Dark Lord" seems to only be a title, and no known dark lords have gained or lost any power upon receiving the title. However, if the Chosen Undead chooses to become a Dark Lord, several primordial serpents will be seen bowing before them. No other dark lords seem to have any relation with the serpents, so the meaning behind this action is unclear.
Dark Souls IIEdit
Dark Souls IIIEdit
** While Vendrick was quite able to have linked the fire, he was not yet understanding of the circumstances until it was too late and chose instead to seal it away rather than give Nashandra access.
*** It is implied that Lothric never actually linked the fire despite being destined to, instead he chose to watch from a distance as the fire faded.