Somehow, when they were all young adults, a curse was placed which would kill Eva. Blue Fairy stepped in and provided a protection spell, a magical cuff, but it would only protect Eva until a new royal was crowned. When the new Princes (Snow) came of age and was crowned, Eva would die.
When the time came, and Leo was ready to marry again, he roamed many lands looking for a new woman to love. Rumple might have seen that WWW would be important to him one day, and might have helped Leo find WWW who at the time was lovely and kind. They fell in love, and plans were made to marry one another.
Cora had other plans however, she wanted her own daughter to be Queen. Rumple working with Leo angered Cora and a battle began. With the help of Black Fairy, Cora cursed WWW green and banished her from the kingdom into the land of OZ. As punishment for her bad behavior, Black Fairy was also banished to OZ.
WWW was awakened by the use of the black wand. She wants the kingdom that was promised to her by Leopold. She wants Regina’s life. She wants her friends. She wants her magic, and she wants to take the love that is blossoming between Regina and Robin as her love was taken away from her.