Marriel Stein is the wife is Franken Stein. She was a witch. And is deceased.
Their is not much about Marriel. It was said by Stein that's he's known her since they were teenagers. They met in a forest while Marriel was writing a book. He wanted to experiment on her, so she let him. After he did it didn't react to her at all. Then Stein and Marriel started to fall in love with each other. Then he got too far with her and got her pregnant at 16 and had a baby name Candy Stein. But after Marriel had her baby, Marriel had to tell Stein that she was a witch. Which surprised Stein, but he loved her anyway cause she was a nice person. But, Medusa at her snakes spy on Stein, which made her jealous. But Medusa waited for Stein to have another baby to how the other one acts out. Then, after Stitches was born, Medusa came and killed Marriel, due to her being jealous.