Deadly Mistakes Wiki

Jennifer with and without her hat

Jennifer Xylene Tennyson, or simply "Jen", is the daughter of Ben Tennyson (Ben 10) and Lucy (Elfen Lied; referred to as Kaede in-RP). She also has an older half-sister named Kimiko.

Early History[]

Ben and Lucy met as children in New York shortly after arriving there as a stowaway on a plane. Lucy left Kamakura, Japan shortly after killing the four orphanage children to avoid being found out. Before Ben, Gwen, and Grandpa Max came along, she had been staying with Kevin. After it was discovered that Lucy had nowhere else to go after Kevin was dealt with, the Tennysons took her in. It didn't take long, but Lucy developed a crush on Ben during that summer, and Gwen caught on to it rather quickly. However, it wouldn't be until the events of Alien Force that Lucy finally revealed her feelings for Ben, and they have been together ever since, married and everything.

About a year or so after their marriage, Lucy found out she was pregnant, and later gave birth to Jennifer. Jennifer resembles her mother so much, it's almost scary. The only real difference between them is the hair and eye color. She also inherited her mother's vectors, but due to her human blood, they are not as powerful as Lucy's. They can pack a punch and lift heavy objects, but they cannot slice through them most of the time. To make up for their diluted power, Jennifer instead has six vectors with a full range of 2.5 meters. Ben was pleased with this result, but Lucy was not. She feared that other kids would ridicule Jennifer in the way that kids did to her and that she would become murderous as a result of said ridicule. For this reason, Jennifer is homeschooled so that she could have limited contact with other children. Jennifer does not particularly like this, but she knows and acknowledges the fact that her mother says it's to protect her. She is good friends with Delon, her next door neighbor, who is also homeschooled. He knows of her horns, and actually thinks they're cool, much to the Tennysons' relief.


Jennifer is very much like her father in terms of personality. She is a major tomboy who loves adventure and has a tendency to get herself into trouble sometimes. She loves her parents very much, and could not be prouder to be her daughter. In fact, she even aspires to become a Plumber like her father someday.


  • She is a relatively rare case of "in name only" in the RP. This is because her birth wasn't truly a mistake, given that her parents are happily married.