In Norse tradition, there are a variety of spirits called "wights". They are divided into the landwights, house wights, alfar (elves) and swart alfs (dwarves). Within the alfar category, there are two different types: Light Alfs and Dark Alfs (Ljossalfar and Svartalfar). They are often strongly misrepresented and misunderstood, due to their popularity in fictional works. The original word for Alfs meant "white/light"- a word that was significant to the Alfs character. They were assumed to be entities with a great deal of spiritual and magickal "brightness" to them.
Moreso than any other race from Northern traditions, the Alfar are believed to be the ones who work most with magick. Other races from this tradition work with and use magick, but not to the same degree."The key to understanding both the light- and dark-elves is that both races are folk who live and breathe magic. They are magic in a way that other folk - even the Aesir and Vanir - are not."(Raven K) One of the things they live and breathe is glamour. Just like the jotun have a cultural concept about their appearance (often wishing to be perceived as strange or ugly) the Alfar use glamour and perceive themselves in a certain way.
But this can be dangerous. It's important to realize much, if not most of Alfheim is covered in glamour- the trees, the rocks, everything. If you are not skilled in recognizing and seeing through glamour, it would just appear beautiful to you. However, if you are, it can become increasingly frustrating and hard to pathwalk because you will see the glamour AND what it really looks like- almost double vision. It's also an unspoken rule that you never, ever try to see past a glamour that the Alf is projecting upon itself. If for instance a small alf is glamouring itself to look taller, you shouldn't try to see what it really looks like. This is like peeking up someones skirt, and you're bound to upset them to a great degree. It's a high offense.
The Alf have the potential to be very dangerous, never forget that. It's said that many who spend too long working with the Alf will go mad, or find it harder and harder to come back into their bodies when they pathwalk."Alfs are also well-known for 'alf-shot' - little invisible arrows which cause effects in humans and cattle ranging from sudden sharp pains, local swellings, and inexplicable wasting sicknesses to bone cancer and even death. Lumbago and arthritis are especially thought of as the result of alf-shot."(Gundarsson)
Snorri describes the Light Alfs, or Ljossalfar, as appearing to be bright, shining spirits that are very fair to look upon. They orient very closely with the Sun. In general they are considered to be very airy spirits. Size-wise they are supposed to vary from much smaller than a human to much taller, though not as tall as the Jotunfolk (Giants). They often appear very beautiful, but have an inhuman nature to their appearances. The Light Alfs are often said to appear as being tall, with various shades of blonde in their hair, pale complexions and blue eyes.
Personality wise, they tend to hold themselves in a very quiet and regal manner. However, they are Alfs, and in the blink of an eye they can turn hateful. They are not opposed to hitting people. It can be very easy to offend them, and that should be avoided at all costs. They have a knack for being very, very vain. If you want to get on their good side, a smart move would be to compliment them. LOTS.
Their culture is very different from the Dark Alfs. They tend to group themselves in "Houses", and have nobles just like we do. Their nobility is the "top class' and often behaves in the way you would expect. They tend to disregard most people, as they have their own set of customs and traditions. It is not common for a person to be invited into their castles and homes. You'd have far better luck mingling with the commonfolk. A keynote is to be weary of the time you spend here: it's often said that the longer you stay, the more irrelevant time becomes to you, and their are stories of people getting stuck here and living their lives with the Alfar.
Far more is actually known about the Dark Alfs, or Svartalfar, which are sometimes referred to as the Mound-Alfs. Dark Alfs are believed to be spirits of dead folk. The norse word for male elf translates to an irish word meaning "ghost of the dead". The name Mound-Alf refers to burial mounds, again reinforcing the idea that they are spirits of the deceased. They live in Svartalheim.
They are known to be more unkindly disposed to humans, and more likey to mess with them. It used to be believed that Dark Alfs would sit upon a persons chest as they slept and whisper nightmares into their ears.
Like their counterparts, they are capable of glamour and often how they appear is not how they are. Their glamour, however, tends to not be "light" and "beautiful" like the Light Alfs. Dark Alfs are known to love singing. In fact, it is said that most of their speech is actually sung. They do not often come out during daylight hours, and prefer to be active at sunset. They tend to behave in a very sadistic, devious, secretive and deadly manner- which is one of the reasons they are seperated from the Light Alfs. In their culture, women are actually the dominant gender and have the higher status. The symbol for a female dark alf is a posionous spider- a very fitting symbol.
It's important to be cautious when working with the Dark Alfs. They are known for their ability to move silently, and stalk prey. It's not uncommon to hear of someone being tormented, harassed and chased by Dark Alfs. They do not see much value in telling the truth, in keeping oaths, in honoring deals, or in keeping their visitors alive. Their moods can change in the flash of an eye, and just because you are being friendly does not mean they will like you.
Things to offer to them: Sweets and candies, spiders and insects, beautiful and shiny trinkets. Don't be offended if the Dark Alf ends up completely destroying your gift right in front of you. They have a knack for smashing things,especially mirrors.
Elves, Wights and Trolls by Kveldulf Gundarsson