Frankenstein thought the creature was attempting to detain him...... he was horrified and somewhat frightened. The creature reaches out with a grin on its face because no matter its size..... it has just been born. It is an infant seemingly reaching out to its parent.
He held up the curtain of the bed and his eyes, if eyes they may be called, were fixed on me. His jaws opened, and he muttered some inarticulate sounds, while a grin wrinkled his cheeks. He might have spoken, but I did not hear; one hand was stretched out, seemingly to detain me, but I escaped, and rushed down stairs. I took refuge in the courtyard belonging to the house which I inhabited; where I remained during the rest of the night, walking up and down in the greatest agitation, listening attentively, catching and fearing each sound as if it were to announce the approach of the demoniacal corpse to which I had so miserably given life.