There is a lot known and not known about ridgerunners in The Wingfeather Saga. I've written less than a handful of fanfictions regarding ridgerunners and their... tendencies. (Keep in mind I haven't finished the books yet so these may not be accurate). Here is my list of "headcanons" or rather, "thoughts" on these little fruit loving creatures:
There could be good ridgerunners out there but they are few and far between. I theorize there are trustworthy versions of these creatures throughout Aerwiar but it's so rare that you mind as well not even bother becoming friends with them... Unless you're looking for an interesting time. I've written about a ridgerunner named Zarabean who was a troublemaker who became a ridgerunner after a visit from Anniera's Lore Wain. He learned about the Maker and decided from there on out he was going to try his best to live the right way and quit stealing from others. This caused some trouble with his family and tribe but they eventually followed in his steps.
The Killridge Mountain Ridgerunners tend to live in the forests led by their selected elders. Much like The Hollows' Keep, ridgerunners have elders of their tribes that make the final decisions regarding their people. I speculate there are tribes throughout the forest that don't necessarily work well together. Politics and all that.
The ridgerunners in those areas have patrols like The Durgan Guild. This is a funny little idea but what if they use codenames that are fruit related across the land to avoid suspension to the hollish people? Their patrols would consist of avoiding Durgan Guild members, looking for fruit, looking for ways to get fruit by finding weak points in their defenses, and deciding whether or not the risk is worth the quality and quantity of what they were stealing.
Ridgerunners who were taken from their tribes are usually rather depressed. Despite being (usually) selfish creatures, they still have a value on family life. This loneliness only adds to their cruelty if they were bribed into a nefarious cause. Not to say you should feel completely bad for them as many CHOSE their line of work with the fangs, but know there could be a few ridgerunner slaves out there.
Their life expectancy can be rather long if they weren't so bent on being thieves and living in toothy cow infested woods. In one of my fanfictions, a character that was a bad ridgerunner that turned good lived to be very very old- into his 100s! Some think that they could survive long simply because of their balance of fruit and physical activity but don't quote me on that. I'm not a doctor.
Very few of them are content with living on the ground. They naturally feel safer in the trees or higher heights due to their instinct to avoid being eaten or captured by other creatures. They aren't very tall beings.
As for their appearance, from what I've seen in the WFS and the show, the ridgerunner averages between the height of a 3 year old toddler to the height of a 7 or 8 year old child. They're not very big and their twiggy in their appearance. I think the younger ridgerunners could pass off as children if their noses and ears were not so prominent. In my one fanfiction, I was exploring the idea of a ridgerunner passing herself off as a child to get into the Hollish school. Her features hadn't grown into their full ridgerunner appearance so hiding her ears made her pass as a human kid!
Different ridgerunners might have "preferences" or a favorite fruit. While most ridgerunners will eat ANY and I mean ANYYYY kind of fruit offered to them, I believe there would be some that had preferences. I've owned guinea pigs for years and I tell you, they don't all like the same fruit and veggies every time. If animals can have preferences, ridgerunners can too. You might have some picky ridgerunners on your hands! I hope you got grapes if that's their favorite!
The closer to Dang you get, the more confrontational the ridgerunners become. I imagine they take any opportunity to rob a traveler of fruit and that's no different in Dang except it's worse. Not many travelers mean to end up on that side of the mountains on purpose.
They could be capable of complex relationships. This means they could very well learn to live among their kind or among humans, which are the main kind of sentient being. However, being capable and acting being are two different things. Most ridgerunners would rather perish than have a friendship with a human or a meaningful relationship with another ridgerunner. Tread carefully if you're considering..
And those are my thoughts!! What do you think? Do you have any ideas for these little creatures? Let me know!
I made a little registration card other sentient species could obtain for citizenship in the Hollows-