Blindheims have a fascination with tales and objects from the surface world, particularly plants and other natural items. They gather in the depths of the Underdark near routes used by merchants and other brave travelers. They typically make a cautious approach to stronger creatures, speaking in halting, croaking Undercommon to offer their services in return for fresh food, metal weapons, and trinkets from the surface world. But when they have superior numbers or engage creatures that appear weak, blindheims will often ambush to take what they want.

The blindheims speak of an ancient era when their folk dwelled upon the surface. According to their tales, their ancestors stole a piece of the sun, then fled to the Underdark before devouring it and gaining the ability to project radiant energy from their eyes.

Blindheims fear that some day the sun will venture underground and have its revenge upon them. When dealing with surface dwellers, they insist that visitors swear to never tell the sun about them, and ask endless questions about the sun's actions, its anger, and its attitudes. But surface folk who attempt to soothe the blindheims' fears often cause these creatures great offense. In the minds of the blindheims, the sun could not possibly have forgotten their great and heroic theft, and anything said to dispel the belief that they remain infamous and feared by all folk of the surface rouses their anger.

Some Underdark creatures, particularly the drow and kuo-toa, raid blindheim settlements in search of slaves. Although the light from these creatures' eyes is a formidable threat to these raiders, a captured blindheim is a useful living weapon.