The Bed Demon was a demon created from a mixture of the remains of Raven's spell book and bed. It attempted to frighten Silkie, before being consumed by the larva.
After Silkie ate Raven's spell book, he burped a gas which melted Raven's bed. Silkie licks up the liquid and burps another gas, creating the Bed Demon. The Bed Demon roared at Silkie, but the mutant larva swallowed the demon up while it screamed in terror.