As the War continues on Fódlan Marianne ran into the forest to get away from everything, she always claim that her crest is the blame for everything she even blames herself, as she buries her face in her knees crying her crest begin to corrupt and her eyes turn Animalistic red, she grew fangs in her mouth and her nails became sharper. She Did Not turn into a Demonic Beast But she is acting like one due to her crest, the shy and pessimistic marianne became a "Demonic Beast Marianne"