>>96383991
She's always the same, she just looks different to everyone based on what they expected to see the first time they saw her. She looks humanoid to Andris because she had been forcing her to sleep in the woods while on walks and was reading her dreams. Her first communications were implanted dreams and Andris saw her as a humanoid. That's what she expected when she sees her in person.
Skog's mood changes how she looks in those forms though.