These guys were basically made for adopts, or at the very least a way to output a specific bit of my creativity. Arvytus have very unstable genes which cause many mutations and the pups usually only have a couple of things in common with parents. This allows for a very quick adaption in and environment that is regularly changing by magic deep deep within the planet. Although magic users are unheard of, the landscape is in turmoil and anything trying to live there must expect the strangest of sightings.
For their best survival Arvytus often form packs of 5-10 generally with a single leader who is generally the strongest, or otherwise skilled enough to beat the previous leader. These packs are generally nomadic but can be found having settled in areas that fit their needs. Though these den sites only last for about a generation before the land changes making it uninhabitable.
Arvytus range for 4-5 feet at the shoulder with wildly varying wingspans. In most cases they can only fly for an hour at a time before they become exhausted or otherwise have to land. While they can and will fight with teeth and claws, those assets are often weaker than most predators found on Earth, rather, and Arvytu's best weapon is their tail which is thick and muscled and easily used as a club to fight.
Arvytus are apex predators thought they still have to fight against other large and formidable foes who are also trying to live in this land...

Womrels are very large and very hardy creatures who are very familiar with dangerous environments. They survive in harsh landscapes not only with brawn, but with the deep bonds formed with pack-mates.
Although Womrels have a very threatening appearance standing well over 5ft, they have been known to form unbreakable bonds with pack members and even individuals of other species when mutualism occurs. These bonds allow survival in landscapes deathly to individuals by increasing the chance of successful hunts and the survival of cubs. It is of very rare occasion that a member of a Womrel pack is kicked out or otherwise removed from the pack. Such an istance has a high tendency to leave all Womrels involved in a saddened state.
The earliest recorded Womrels were stationary and claimed large areas of land to hunt and live off of. This behavior can still be seen today, however it is most common for Womrels to instead live nomadic lifestyles, following their prey as herds migrate throughout the seasons. This can be quite the scary event if you happen to be in their migratory path but it is often possible to safety observe Womrels from a distance as they are quite placid so long as you keep your distance and don't smell like food.
Womrels are very formidable foes, however they are not apex predators. Not only do Womrels have to watch out for smaller carnivores who prey on undefended cubs, but a bigger beast, the rare Dolbsas, which can tear a Womrel pack asunder if caught off guard.