I drew my hc for the developmental stages of Puffs:
Newborn-Young Child: A newborn Puff is born with a thin layer of velvety fur, which is not very good at keeping them warm. So, the parents must be sure to keep their newborns warm enough until they can regulate their own body temperature. If the parents have the right genes, the Newborn will be born with a small pair of wings on their back (be it feathered, bat-like, insectoid, etc) which are currently incapable of flight (And covered in down if feathered). Since the mother cannot produce milk for a newly born puff, they are promptly fed nutritious foods high in Folic Acid, DHA, Vitamin C, etc. During their early stages, Puffs require a lot of food. Some say that Puffs have stomachs like black holes... And they would be correct.
Adolescent-Teenager: If they have them, the wings would start to fledge and allow flight. It is also at this stage that a Puff will sprout horns if the genetics line up. The fur grows thicker at this point, but it will grow to only about the length of a shorthair cat for the rest of their lives. Their baby teeth fall out and are replaced by a set of sharp fangs, though they’re still growing in. Their “nubs” have developed as well, and are now more paw-like. These paws can now hold objects more securely, but these are also still developing. Puberty has set in for the young Puff, and their reproductive organs are beginning to mature.
Adult: Horns and/or wings will have developed into their full size, as well as their paws and fangs (it is to be noted that if the Puff has venomous fangs, the teeth will be slightly longer than most and seem almost vampiric). Reproductive organs have also fully matured, along with the mind. Puffs typically live for a very long time, usually ranging from several millennia to several eons.
Puffs are considered a mammalian species, though like the platypus they have a strange quirk to them. While they have fur and give birth to live young, the mother is unable to produce milk for her newborn. So they must eat large amounts of food to make up for it. Every ounce of food they consume is used. Therefore, Puffs are physically unable to produce waste.
There are a certain handful of traits a Puff can be born with, the most common being wings and horns. A rarer trait that has cropped up is venomous fangs, wherein the fangs are lined with a venom specific to that Puff, making a universal antidote incredibly difficult to procure. When they are a young child and an adolescent, the growing Puff is able to access an array of copy abilities to test out. Usually, by the time they are a teenager, a Puff will have settled on one to two copy abilities and lose the “testing ability”. In rare cases, a Puff will not lose the Testing Ability and get to keep the ability to freely use every copy ability.
Magic in Puffs is also a fairly uncommon trait. Like all new magic users, it must be tamed and the Puff must get special education to learn about their abilities. If magic is left untamed, it will only harm the young Puff.
Male Puffs are called a Tiercel, Female Puffs are called Does. A newborn/child Puff is called a Puffling, and the adolescent/teenage Puffs are called Fledglings. A Puff who is expecting is called a Queen. There is no reliable way to determine the gender of a Puff (other than asking them). But typically, males are very slightly bigger than the females.
Puffs are typically social creatures, and often settle in large groups called Clans or Squadrons. These groups often settle in serene locations that are tucked out of sight by nature, forming towns, villages, and cities. It is commonplace for these settlements to by named after constellations. Within these settlements, the practice of naming newborn Puffs after things of a certain theme has become common (ex: Naming newborns after desserts and treats in the village of Pavo, and naming them after stars in the skin in Alioth).
Puffs typically mate for life, and males dedicate lots of time into impressing females (or whatever gender suits their fancy). Competition is fierce at times, and the most common methods of courtship are fights with other males or presenting the female with interesting or valuable objects such as stones or relics. When the female has made her decision, a pair of matching brooches that are unique to the couple are forged as a form of engagement ring. Raising Pufflings requires the efforts of both parents, and infidelity is considered a very shameful act. If a mate dies, is separated from them, or leaves them, the other Puff can choose to find another mate if they wish.
While Puffs are social by nature, loners who do not belong to a Clan are common. Usually, the main cause would be territory loss due to widespread Puff massacres, but at times Puffs either leave their Clans for a life of solidarity or to contribute service somewhere else, or are at times driven out of their own clan.
Stereotypically, Puffs are considered noble and driven, while also being scary strong in battle. Puffs have become symbols of bravery, virtue, freedom, dedication, strength, and wisdom. While young Puffs have become symbols of innocence and potential. It is commonplace for Puffs to be recruited into armies, guard forces, patrols, guilds, etc. for their sheer strength alone. However, a negative stereotype that venomous puffs are naturally aggressive and are to be feared has caused many Puffs with venom (and those assumed to have the trait) to be driven out of their clans and mad loners.