Thanks to Merlia W for following!
Edit 06/10/15
William Joyce is participating in Inktober in the lead up to the Jack Frost picture book, and he's also releasing some little bits of information on his Instagram. Including the fact that vampires and werewolves exist in this universe. So yeah, had to change the werewolf bit.
If anyone wants to look his Instagram name is heybilljocye
Signature colour-grey
Signature weapon-none
Symbol- Non HOG-dog paw print, HOG-fir tree
These Descendants weren't a threat or even aware of their heritage until five years after Pitch's most recent defeat at the hands of the Guardians. Most of them appear to have the ability to change their shape into a wolf at will, and may also be able to manipulate shadows to a greater degree than the Descendants of Pitch.
In human form their eyes are wolf like, which can range from yellow, amber, grey or brown. Their hair colour is the same as their coat colour in wolf form, which in the case of the group that attacked Jackie was black. Unlike normal wolves who have varied coat colours, Descendants of Lupine usually have a solid coat colour.
The transition between human and wolf varies depending on the amount of practice the individual has. The more practice, the, swifter, smoother and more painless the change. However, the more they change, the more their human appearance becomes wolf like. Some have that kind of face anyway, but for some their canines become more like fangs and their ears become elongated. In extreme cases excess body hair can grow in strange places.
They have a greater command over shadows than the Descendants of Pitch, using it in a similar way to Dream/Nightmare Sand. They can also use it to shadow travel.
While they cannot create and directly command Nightmares in the same way as the Descendants of Pitch, they can 'tame' them. If a single Descendant can get onto the back of a Nightmare, they can make it do what they tell it to as long as they are in physical or shadow contact with it. It cannot be tamed indefinitely and once released it will either be destroyed or return to the Descendants of Pitch. This is a trait any 'dark' Descendant has, but it is rarely utilised.
They appear to have a pack like structure, and those that follow Lupine are the most animal like. All of them are nomadic, travelling around the world and officially they don't exist.
In most packs they have a human approach to breeding, anyone can as long as they both consent. However the more animalistic packs have a wolf like approach, only the dominant pair breed. Because of their shapeshifting nature how Descendants are born is more complicated. If offspring are conceived while the parents are in wolf form, they will be shapeshifting Descendants, no exceptions. If they are conceived while the parents are in human form, they have the same chance as any other child of a Descendant to be a Descendant.
Children who are not Descendants born into a pack are usually left at orphanages after a few years, four or five. It depends on the pack. It is done at this age so that the child remembers their heritage and passes it on so that when a Descendant is born into their family again, in theory the parents will not panic and pass the child to a passing pack.
The "Black Furs" are Lupine's elite, twenty to thirty Descendants with the highest raw power. Pete's pack were in high up in the Lupine's eyes, but Pete died and was replaced, the new leader pulling them out of the "Black Furs". Contrary to the name you do not have to have black fur to be part of the elite, it's just that all of the original elite had black fur, so the name stuck.
Most packs are similar to HOG Branches, constantly on the lookout for potential Lupine Descendants. Several packs respect Lupine and are interconnected in some way. There are however, neutral packs.
Tracey's pack is a neutral pack. They keep in contact with other packs, keeping their pack leaders up to date with the rest of the happenings involving the Descendants of Lupine and any other pieces of information. Because of this they know more about the world than they appear to.
Neutral packs are a majority and consist of those who do not wish to follow through with Lupine's plans. Descendant of Pitch 'traitors' can find safe havens with these packs, having gained the courage to do so when Penelope turned traitor. Many other Descendants who do not want to follow the rest of their Descendants with what they're doing can join these packs as well.
After the Battle of the Undead HOG and Tracey's pack become affiliated, but the pack is not truly a part of HOG. This was a request from Tracey herself. After a while there were three clear factions among the Descendants of Lupine, one loyal to Lupine, one neutral and one that was loyal to HOG.
It is assumed that they have increased senses in human form, but it is unconfirmed.
They have no geographic preference.
They are not related to werewolves.