Ontos are the remnants of a race of thunder demons that were created for an assault on the human world.
Examples of ontos:
Ontos are characterised by their feathers, their large noses, and by their leathery wings that are anchored at the collarbones. They typically have ram-like horns, flukes on their tail, and some scaling on their bodies.
Though ontos are capable of flight, they largely choose not to. They don't have very good wings, and flying is hard work for them. Ontos use their wings more for balance, hugs, and wair (wing-assisted incline running). They prefer to fall into flight than take off from the ground.
Ontos lose weight very quickly when they're ill, so they consider it a good idea to carry some extra fat to be a buffer zone. This is why you rarely see a skinny ontos.
Ontos horns are largely useless in battle, so ontos will rarely attempt to use them. They are quite wary of even trying, because their horns can be useful handles for their opponents to grab. For the same reason, ontos will rarely try to bite an opponent even though they have strong teeth - biting an opponent brings the horns within grabbing range.
Ontos are demons of thunder. The vast majority of ontos (over 95%) also have a secondary element at their disposal. Most ontos don't get great distance with their magic attacks, and prefer to fight by using their elemental attacks at close range to supplement their physical attacks.
Ontos are the evolved descendants of an artificially-created demon species, the pedre-ontos. The pedre-ontos proved unfit for purpose, and were abandoned by their creator. Most created demon species are made for a specific purpose, and then die out once they are no longer needed. However, the pedre-ontos had sufficient adaptability to survive on their own and prosper.
Most modern ontos are mixed with something else, as a result of the pedre-ontos interbreeding with other species as they spread and evolved. (Silrathus and her family are part minotaur, for example. Krog and Murgatranthes have some harpy in their family tree.)
The ontos' tenacity and success is seen as an aberration, and they are looked down upon by most natural demon species for being 'fake'.
Ontos' fleshy eggs are more like single-use external uteruses than typical eggs. Eggs start small upon being laid, then begin to extrude a network of tendrils and gristly webbing. The tendrils absorb organic and magical matter and use it to sustain the developing embryo, and the egg grows in size with its occupant. The egg's parents will leave food items out for the egg-webbing to absorb. Ontos dispose of their dead this way too, letting the flesh of the deceased sustain the next generation. (Most demon species consume their dead in some way. They find it odd that humans tend to burn or bury their dead. Why waste all that perfectly good flesh and magical energy?)
The egg-tendrils are mobile and can catch prey that moves too close. Entanglement must be broken immediately or absorption will begin. The egg's immediate family have immunity to this (although even they would get absorbed too if they stood absolutely still for several days). Ontos usually lay no more than one egg at a time. If two eggs are placed too close to one another, the stronger egg will absorb the weaker despite the degree of relation.
Ontos gestation lasts for 2-5 earth years, depending on the quality of food available for the egg. Newborn ontos can eat solid food as soon as they're born, and can crawl within a few days.
If an ontos is exceptionally powerful, they might undergo metamorphosis at the age of around 1,000 (Earth years), and assume a more powerful form known as an 'elder'. An individual who becomes an elder (probably 2% of the population) will live longer than an un-metamorphosed ontos.
In theory, an ontos who lives long enough will metamorphose again into a third form, which is what the created pedre-ontos were supposed to have been all along. This has yet to actually happen.
Ontos are omnivorous - very omnivorous. They can eat almost anything humans can eat (besides rosemary, which is toxic to demons), and more besides. They can eat rotten food with no ill-effects. Ontos can subsist on a carnivorous, herbivorous or mixed diet, as their internal plumbing will adapt over time depending on what foods are most available. Like crocodiles, ontos can continue swallowing after they're full and store the excess food in the oesophagus until more room becomes available in the stomach.
These demons are most at home in highland forests and plains. Ontos are quick to move into and revive abandoned settlements and ruins.
Ontos typically live alone or in pairs or small groups. They enjoy allopreening (of their feathers) as a means of bonding, and form very close friendships.
Though ontos are absolutely open to forming friendships with demons of other species, they tend to keep to themselves because a lot of non-ontos dislike them. Ontos may appear cold and disdainful at first (which probably doesn't help to dispel any negative impressions of them), but they are simply keeping their guard up until they know it is safe to drop it. They become much more animated and open once they have warmed to a non-ontos.
Ontos are a somewhat odd mix of being proud and not taking themselves terribly seriously. They are proud for having rejected the will of their creator and choosing their own purpose instead of conforming to the one set out for them, and they are proud for having survived this long despite being intended to be a throwaway species. However, they are simultaneously aware that they were not 'meant' to be, and see this cause for relaxing and celebrating because they don't have any great purpose to fill. This mix of traits means they do get on with humans a little better than most demons - while they do still have the typical demon arrogance towards humans, most of them aren't too proud to talk to us.
Ontos have five sexes (enig, thed, seml, bren, obon). They have no discernible physical difference besides the shape of the gonads, which are internal. (They are in the base of the tail and can be identified at birth if the newborn's tail is held up to a very strong light.)
Ontos don't have genders as such, because of the lack of sexual polymorphism. There are some stereotypes about how each sex behaves, but this is viewed more along the lines of how humans view horoscopes (we know it's rubbish but we have fun with it anyway). Ontos know that they will probably get labelled as either male or female by dyadic species, and most of them just go along with it and don't really care.
Each ontos sex can reproduce with any of the other four (only one individual in a pairing will lay eggs, depending on the combination of the sexes). This was set up by their creator (more accurately: the creator of their precursors, the pedre-ontos) to maximise reproductive capability, as it meant that any given individual could potentially reproduce with 4/5ths of the population instead of just 1/2.
When in public, ontos typically wear trousers or skirts at a minimum. Public nudity is acceptable, but seen as vulgar.
Ontos are good at making underwear. At least 30% of underwear in the demon world is of ontos manufacture.
Ontos are gentle, as demons go. They'll enjoy messing with an unprepared summoner, but are unlikely to do anything cruel or twisted to you. They're more likely to helpfully point out where you went wrong. Ontos are also surprisingly adept at learning to use human technology. Despite these positive traits, ontos are not widely employed by summoners. They are seen as a demon for low-level magicians, and they can be quite temperamental. Ontos expect to be fussed over and praised a lot by their summoners, and they can get stroppy and break stuff when they aren't, which gets very taxing on a magician's patience. There is also the fact that many other demons look down on ontos, and by extension will be less likely to work with a summoner who employs them. On the other hand, ontos can end up being very loyal to their summoners, as they don't have many allies.
It might be wise to employ two ontos at a time, so they can preen and occupy each other, freeing the summoner from having to take time from their work to placate them. Of course, employing two demons is twice as expensive.