Aos si have these basic fey powers:

• Aos si can vanish and become insubstantial by speaking their True Name into a mirror.
• A circle of salt will protect an aos si from supernatural powers for as long as it goes undisturbed.
• Any aos si being may summon a faeriesteed or fey deer by whistling three special notes.

Aos si hang bells on their steeds because the jingling will keep unseelie fey away.

They see the True Name of other fey beings if they have eaten the right mushrooms or if they have a piece of hair, a tooth, fingernail, or other part of that person that has been given to them or discarded. With these Names, they can command these other beings vocally.

Every aos si can access their ancestral memory through very old songs, but they can only bring up fragments, intuitions.

An aos si can command the elements and nature through simple formulas: crushing a dried leaf to make plants grow, humming a special song to influence animals, rubbing ash between their fingers to control fire, looking through a hagstone hung from their neck to command earth and rock, raising a hawthorn stick to the sky during a storm to call down lightning or shift clouds where they point, blowing a dandelion puff to redirect the wind, reciting special rhymes at water to make it flow where they will, or bathing in the moonlight to be able to absorb and redirect its glow.

The fairy rings, mounds, paths, forts, lochs, woodlands, or trees that belong to the aos si are protected by their powers. If someone violates or disturbs their spaces, the aos si who is responsible for that particular location or object will be able to curse the violator with ill fortune, cast glamours to drive them away, or bind them into the Dream Realm. They can imbue their special locations with wards of illusion by painting on them in indigo dye. If someone enters their home with ill intention, an aos si will sense them and be able to confuse or distract them with illusion.

Hawthorn trees are special to the aos si. They draw from them beauty. If they wear hawthorn leaves, they have an aura of stunning beauty, so long as the leaves are fresh.

Many aos si can fly, whether they have wings or not. Very small aos si learn the language of birds and ride on them if they cannot fly; most can fly if they jump from a ragwort stem.

If a mortal or other fey sees through the glamour of an aos si, the aos si will be able to alter the memory of the viewer by whispering a special rhyme that will make them hard to remember. An aos si can create fairy lights by snapping their fingers on a twig. Fairy lights appear in the distance and lure folk away. They can create fairy ointment from the nectar of a morning glory and tea made from toadstools. This ointment will dispel illusions if placed on the eyelids of a mortal or another fey; it will soothe an aos si in distress. If an aos si realizes the ointment has been used to reveal them, the user will go blind.

If someone eats food in the home of an aos si within the realms of Faerie, that person will be subject to one of several enchantments: losing their memory, being trapped among the fey, losing time (from a few days to centuries),

An aos si can make machinery turn on or begin moving without touching it if it is not too heavy with iron by tying a piece of string to a bit of silver and twisting it.

Aos si have the following sleep charms:

• They can cause narcosis in someone by dropping a pinch of sand on them.
• They can draw prophecy from some dreams if they have a butterfly in their sleeping area.
• They can tangle someone's hair into fairy locks while they sleep if they have a small possession from that person.
• They can put someone into a hundred years' sleep with an arrow tipped with flint, if they hit at the right spot on the back or neck.
• They can warp someone's dreams to leave them traumatized or subconsciously influenced with a potion of lavender, sweet cicely, and comfrey.

With song, over the course of a pregnancy, an aos si can alter the child in the womb, if they have a personal item belonging to the pregnant person with some emotional value to them. If an aos si makes a pact with someone to serve them, they are bound to it for the duration of the pact. They offer services to mortals and other fey in exchange for parts of their lives, often draining them of lifeforce more quickly, making them dance through the night in their sleep, or taking their physical or mental health. They can transport these folks anywhere, and if a mortal or other fey has their Name, not only can they be controlled, but the Name can be invoked for special powers. They can cause sudden death in children with a hen's egg emptied without cracking it dipped in the blood of one of the child's parents. If they meet a stranger, they can demand love from that stranger and bind them to it with a strange contract with impossible demands if that stranger is attracted to them. If they steal a mortal stranger away, they will leave a wooden replica behind crafted from the mortal's dreams.

Aos si have a predilection for esoteric arts, learning them quicker than other nations. They are especially skilled with words, stones, and herbs.

If they do not speak their True Name backwards into that same mirror in half a minute, aos si lose their True Names. They have a fortnight to recover it or they become targets of the Wild Hunt, corrupted into another kind of fey, or turn into a hag or boggin. Iron or steel will bind an aos si into powerlessness. An iron horseshoe nailed over a door will bar an aos si from entering a house. Most aos si detest tobacco smoke, and it can be used to stave them off. This is just a preference, however, and not a weakness. Uafas harms them.

There are many charms that will keep an aos si away: church bells, inside out clothing, unlucky clovers, stale bread, special amulets and talismans, certain herbs, cock's crows, and St. John's wort.

Every seven years, seven aos si or some replacements must be sacrificed to the Hells because of the Teind.

Aos si are infamous for their interactions with mortals. They are amused by them and often take their trickery and pranks too far, though they don't mean ill, usually. If they are mistreated by a mortal, they can be very cruel. Often, they use their powers over mortals to win offerings of food (cream, butter, fruit, etc.). Because of their touchy tempers, mortals know to treat them with care. They rarely refer to them by name or in a direct manner, hence names like "Good Folk" or "Good Neighbors."

Some aos si make pacts with mortals to give them magical powers, serve them, transport them places, or simply to give them boons. These pacts usually involve taking parts of the mortals' lives, causing them to dance in their sleep or otherwise have their lives taken over by the fey. Some aos si will help craftsmen and such by protecting their homes or work places, doing work for them in the night, or tending their fields. Sometimes, however, their whims find them robbing farmers or millers or other workers for fun.

Nobles among the aos si often view mortal relationships as something to test or play with. Kidnapping of spouses, swapping of children for changelings, and seductions are not unheard of. Mortals often find themselves forced to use trickery or artistry to escape as the aos si take things too far.

The most tragic of mortal interactions, however, is the leanan sidhe, or fairy lover. If an aos si takes a human lover, it will be a brief yet intense life and love affair for the mortal. The mortal is drained of life in exchange for the aos si's devotion and love, and the mortal's life ends in severe mental illness and early death. If the aos si is rejected by the mortal, they become the mortal's slave. If the mortal consents, the mortal is their slave. Rarely, the mortal will find anotehr to take their place.