Beatrice Elster was mentally ill which is part of the reason the Elster Family moved to the countryside. She couldn't take care of Leo and neither could her husband, David, so he made a synthetic, Mia, to take care of Leo instead.
Beatrice later escaped from her carers and took Leo into the car with her to commit suicide. She eventually died after crashing her car into water which killed both her and her son.
After her death, David made a synthetic identical to her to replace her which had a block that didn't allow her to commit suicide. He took the replacement (Later known as Karen) into the woods to kill her but he couldn't as she was 'the woman he loved reincarnated'.
Not much is known about her personality, but she seemed to be a very loving mother until her illness got worse. After this, she became depressed and ill enough to kill herself and her son.
- The memory of his mother playing peek-a-boo is one of Leo's most played back memories.