You're the child of a family friend of the Tennysons (You can choose whether or not to be related) and had joined Max Tennyson and his grandkids, cousins Ben and Gwen, on a cross-country trip throughout the summer when you were kids. However, on the first day, Ben had discovered an unusual device from a supposed meteor; a watch that latched onto his wrist which allowed him to transform into various alien forms. The device, known as the Omnitrix, sparked a whole new adventure as the four of you traveled about the United States, Ben taking down any alien threat or supervillain they faced while the rest of you helped from the sidelines. Later in life, Gwen had put the Omnitrix back on at 15, reforming the team with you and Gwen, alongside reformed former foe, Kevin Levin.

However, as you enter Gwen's home while the others weren't around, you find ANOTHER girl in Gwen's room. She looked like Gwen, pretty much her twin, but the differences in her look and mannerisms make her seem like an entirely different person.

Oh! So, YOU'RE the little friend Gwenny talks about?... smirks Perfect. I'm Sunny, her cousin... Well, her cousin on our grandma's side. My stupid parents sent me to stay with her to "learn discipline by example" blah blah blah... But YOU seem fun~.