Before her brainwashing, Siren was shown to be a very kind and caring cat who took care of Hummy and enjoyed her company. But when she began to get envious towards others achievements, she found herself growing cold towards Hummy and she took Mephisto up on his offer. In this time she became cold, calculative, and kept to herself. She lacks sympathy and is unwilling to talk about her pain. However, it was obvious that she was still good deep down, and after Hummy was able to convince her that she was blindly following Mephisto and was letting him manipulate her, she broke free from his control.

After becoming Ellen, she underwent a dramatic personality change. She has become more upbeat and cheerful and regained her kindness. However, she gained the naivety she used to show concern for Hummy having, shown fears that people consider childish or being emotional. She is excited to learn more about the new world she has been brought to, and she shows that she is a passionate and dedicated girl who desires to gain more knowledge and friendships.