Pixies are small beings composed entirely of magic and a fragment of a human soul. They look like tiny humans with large wings and brightly colored glowing skin.  They are immune to nearly all diseases, are invulnerable to any physical damage or injury, and do not require food or drink as humans do (although they will still eat it for the taste). They do not age in the same way as humans, as they appear to be in early adulthood for their entire life. However, they do go through a long mental growing period, and cannot even speak until they're around the age of 6. As they grow older, they become more attuned to their Bond, and are able to stray further and further away from their human. In their infant years, the range is only a few feet, but it gradually extends until it encompasses the entire Earth around their 30's.

Pixies are curious creatures and are generally purer at heart than their human counterparts. They often enjoy collecting small things that interest them and decorate their hutches with those objects.

This mist is what pixies feed off of for sustenance, by way of respiration. Pixies describe it as "a slightly sugary flavor on the back of your tongue every time you breath in".

The Bond is the term used to describe the connection between a pixie and their human. What it is, is really a shared piece of the original soul before it split into pixie and human. Because of this shared space, both have an intuitive knowledge of exactly where the other is at all times.

A strong Bond means that both parties are healthy in their relationship, and getting along well. Spells are relatively easy to cast and magic and emotions flow freely between the two.

A weak Bond is usually caused by one party (most times the human) cutting off or otherwise damaging core elements of who they are. In Everett's case, 

Pixies can only gain sustenance from the air around them if the Bond is healthy. If the Bond deteriorates to the point where it is severed, the pixie will die of starvation, as they can no longer access the "food" around them. Without the pixie the human will no longer be able to cast spells or access the Magisphere in any way, and most report an unquenchable feeling of hollowness and incompleteness in their lives.

Spells are a team effort between humans and pixies, and neither party can cast them without the other. Pixies provide a source of magic, which acts as a fuel for the spell. Humans provide direction and structure to the spell, weaving the magic together to complete the task required. Humans cannot access or even see magic on their own, and pixies don't have the correct kind of flesh structure to complete any kind of spell beyond spewing raw magic out.

Humans have described the act of having magic pushed through them by their pixie and casting a spell, as "exhilarating, electrifying, and intoxicating".

Pixies are taught early on to not let themselves charge up too much magic when casting, as it could lead to a release of wild magic much like a static shock, with unpredictable and dangerous outcomes for the human involved.

Because of their physiology, pixies are invulnerable to physical damage and could theoretically be immortal, if it weren't for the need for a Bond to allow them to gain nutrition from the air. Because they are beings composed of magic in physical form, all pixies have a 'self destruct button', to put it bluntly. If the pixie so chooses, they can allow their body to dissipate and return back to the magisphere, killing them in a painless way.

This act is referred to as "Spreading to the Winds" by modern western society, and while technically suicide, it's seen as a brave and merciful way for a pixie to die. Normally when a human dies, the Bond is severed and the pixie would die of starvation within a few days. However, rather than suffer a lonely agonizing death stretched out over days, the pixie most times will elect to spread to the winds at the same time the human dies.

When humans are buried or cremated, they are given tokens--sometimes flowers, oftentimes a small clay sculpture--to represent the pixie they were bonded with.