I came across these old Norwegian folklore stories called Huldresägner. The publication was from the 19th century but the stories are much, much older. One story called Qvarnsägner, was split into three and the common theme and setting was mills. The one inspiring this illustration was about a household goblin making hell for the miller.
"Tomten stod midt i dörren, och gapade, och gapet var så stort, att underkäken rörde vid tröskeln och öfverkäken vid dörrbjelken. «Har du sett någon gapa så stort?» sade han."
"His mouth was so big it reached from the floor to the ceiling, and he asked «Have you ever seen someone grinning this big?»
This section of the story frightened me so much I had to made an illustration of it.
Drawn with ink and pencil, A5.