Fairies

Fairies believe they were created to serve nature. They are the ones responsible for protecting it, and ensure plants and animals can develop to their full capacity. This evolved into extreme high regard for life and consequent belief that everyone and everything has an inherent right to life, even if they're horrible criminals or commit unspeakable horror acts. Taking someone's life (and that includes animals as well as people) is the worst thing a fairy could possibly do, because it violates the core of their being and their place in the world. Fairies who kill lose their powers as consequence of going so extremely against their nature. 
Until around two centuries ago, fairies lived in large communities without a central government/administrative structure. They were just groups of people clustered together among the wilderness and the trees, no clearly marked cities or countries. Nowadays, fairies are still reluctant to divide themselves in countries, but they have embraced a more "urbanised" style of living, building groups of houses where before there were only tress and adapting modern technology to their lifestyle. Fairy houses are actually a bunch of individual rooms spread around a specific area. They're not joined together because fairies like to walk outside and enjoy nature as much as possible. The entire area surrouding the individual rooms is filled with trees, gardens, and flowers.

Basic Information

Anatomy

A fairy's power is stored and displayed in the shape of a thin, glowing wing attached to their back. The wing is not physical, however, so fairies don't have the same need as Angels for specially-made clothes. Highly-skilled fairies can change the shape and colour of their wing to suit their mood. A fairy who loses her power (such as Nessa) loses the wing.

Ecology and Habitats

Most fairies live in lush forests, in small communities that may or may not consider itself a city (or party of a larger nation).

Dietary Needs and Habits

All fairies are vegetarian and unable to digest meat. They are not supposed to kill animals, so they never evolved the ability to be able to feed from them.

Additional Information

Geographic Origin and Distribution

Fairies are present in all continents large enough to accommodate a sizeable forest. A few fairies have migrated to urban areas, and fairies captured by demons have been forcefully misplaced.

Average Intelligence

Fairies are no more or less intelligent than the other main races in the world, though they like to believe they have more emotional intelligence and empathy due to their link to nature.

Civilization and Culture

Naming Traditions

Fairies call their children in gender-neutral terms until they are old enough to choose their own. Fairies inherit their mother's surname until their own marriage, at which point the marrying coupe picks a tree to guard their home and takes the tree's name as their own.

Beauty Ideals

Sparkly wings are considered the mark of a happy fairy, so the sparkler the wing, the more desirable a fairy is.

Gender Ideals

Gender identity has no relation to one's body and is developed during a child's first few years of life. Green is considered the colour of motherhood, and thus associated with people who have uteruses, but is not feminine as such.

Relationship Ideals

Fairies are a matriarchal society and practice a mixture of polygamy and monogamy. They tend to live with one partner and the children of any mothers in the family ("mother" here defined as whoever generated the child inside their womb, not necessarily a person identifying as female).
Their worship of "mother nature" and life in general means they place more value in people who can generate life and give birth (of whatever gender). This doesn't mean they directly discriminate against those who can't, but they tend to regard people who have already had children as wiser and "closer" to nature and their Mother Nature Goddess.  Despite pairing up with one person at a time, fairies consider themselves free to have relationships (including sexual relationships) with anyone. Thus, it's not uncommon for families to have many children from different fathers living with their shared mother and a person who is not necessarily genetically related to them, but who has no questions about "adopting" them as such.

Major Language Groups and Dialects

Fairies speak a language called Fadalesh (similar to our world's Brazilian Portuguese). Fairies in different continents still speak the same language, but have developed distinct accents. This is because fairies are all interconnected in ways that transcend geographical distances, so their language did not get isolated enough to fragment.

Common Dress Code

All fairies wear garments that would be classified as "shirt and skirt" in our world's standard in their day-to-day life, with other types of clothes reserved for special occasions and ceremonies.

Lifespan

100 years