I have found it interesting in my study of Felaryan cultures, that while the relationship (in the most negative terms) between the Dridders and the Nagas is extremely well known, the Dridder relationships between the many other sentient species of Felarya have gone silently overlooked.
For instance, while it is still true tha tdridders very often feed on humans, they have also been observed protecting human villages from attack by other predators. Clearly, the motives are not any more altruistic than protecting their food source, and the behavior has been observed in other predator species as well. However, it has been observed that in such circumstances, they can develop a certain respect for particularly effective, or brutal warriors that fight by their side.
Of course, after a conflict has been resolved, the predator-prey relationship between Dridder and Human goes back to its normal state. Interestingly, the Honored status often sticks and a Dridder tribe will avoid simply slaughtering humans who have fought alongside them and will instead give them a chance at fair combat. This seems an odd phenomenon among a species that seems to prefer ambush and pillage over ordered warfare.
Note: This is a slight generalization, though in general, an honored human would be more dedicated to guarding towns than guarding caravans, which are definitely a more likely Dridder target for ambush anyway.
Amongst other predators, Dridders will sometimes seek peaceful relations as long as the other species is respectful of territory. They will also fight alongside other sentient predators in order to fight a non-sentient threat. Like with human villages, as soon as the threat is gone, so is the alliance.
Lone Dridders are also likely to act as mercenaries to other predatory species, but rarely to "prey" species like humans, and they will never fight their own kind as a mercenary.
In some cases, a warrior becomes attracted to the dark reputation of the Dridders and actually seeks to become a part of that reputation. This can happen among any species (aside from Nagas of course) but is most common among fairies, humans, elves and nekos. In most cases, this stems from gaining Honored status with a Dridder clan in one of the aforementioned battles. More rarely, a warrior gains enough of a reputation that the clan has a pre-conceived respect for him or her. In these cases, they may become accepted into the clan as a Dridae.
Note: Though the term Dridae originated from the words "Dridder-Fae", the term refers to any species brought into a Dridder clan.
The requirements to become a Dridae are twofold. First, the member must become honored in battle with the clan that they wish to join. This is done either through mutual combat with an outside enemy, or through single combat with the elder of the clan. In the latter case, the combat is done with non lethal weapons, but a defeated non-dridder is invariably devoured.
The second requirement is a series of rituals, the first involving numerous tattoos that identify the Dridae to other Dridder clans, and the second are essentially mild brainwashing techniques to change the psychological self-identification of the subject to that of a Dridder. Interestingly that the personality doesn't change due to the ritual, though many humans would find a human Dridae to be cold and callous to human suffering due to this disassociation.
Note: In many cases, the second set of rituals is extremely painful. Though the pain seems to be in proportion to the amount the mindset is changed, and may be avoided largely by identifying with the Dridders before the ceremony begins.