In Old Norse sources, trolls are said to dwell in isolated mountains, rocks, and caves, sometimes live together (usually as father-and-daughter or mother-and-son), and are rarely described as helpful or friendly. However, trolls are also attested as looking much the same as human beings, without any particularly hideous appearance about them, but living far away from human habitation. They dislike sunlight and can be turned to stone upon certain conditions of contact with bright light. They are the morbid enemies of wolves.
Tristan Úlfarsson’s uncle Úlfar was revealed to be a troll when he was turned into stone in sunlight. Tristan himself has troll blood.
Upon death, the pillar-like remains of a troll exists with the Dreamworld as well as the Waking world..