excerpt from the article "Norwegian Fairytale Creatures" via Life in Norway

Fossegrimen

Where: Waterfalls and watermills

Much like the nøkk, the fossegrim is a water spirit and shapeshifter. However, instead of lakes and rivers, the fossegrim tends to live under waterfalls and watermills (“voss” or “foss” means waterfall in Norwegian). Furthermore, the fossegrim appears to be much less malevolent than the nøkk, as it appears to want an audience to its music rather than want to use its music to drown anyone. Apparently, it is particularly fond of the Hardanger fiddle. The fossegrim's Swedish counterpart is “Strömkarlen”, whose name translates to “the river guy”.

How to escape

In theory, the fossegrim is not dangerous – unless you're so caught up in listening to the music that you accidentally fall into the waterfall. You may even be able to persuade it to pass on his musical talents.

In the stories of “Fossegrimen Læremeste i Felespill” (The Fossegrim is the Master at Teaching the Fiddle) (ml4090), it teaches a young man how to play the fiddle. The price is a sacrifice, often a young goat or a sheep, thrown into a waterfall running north on a Thursday evening. The teaching process seems to be quite quick if painful, as the fossegrim takes the hand of the pupil and bends and twists it until it bleeds.

By the end however, you'll be able to play as well as any virtuoso – and without the student debt from training at music schools. However, your new-found gift will often depend on the quality of the payment: animals are without much meat on them or that you've already taken a bit out of will result in only taught to tune the instrument, not play it.

excerpt from the article "Creatures in Norse Mythology" via Life in Norway

Fossegrim

The Fossegrim is a water spirit who plays enchanting music on the violin. Usually depicted as a beautiful, semi-clad or naked male, the Fossegrim is tale of both good and bad.

On the one hand, the Fossegrim is sometimes known to teach humans how to play the violin as beautifully as he, but only if they sacrifice a goat. If the goat is too lean, the Fossegrim will only teach how to tune the fiddle.

But a sufficiently prime goat will make for a lesson until the player's fingers bleed at which point they will be able to play so well as to make the trees in the forest dance.

On the other hand, he lures women and children to lakes and streams where they drown, which is rather harsh! But as with all parts of mythology, where good things happen, death is usually close by!