When Ben went with his grandpa and his cousin for the summer, it was supposed to be a family thing only. So why is that you, one of Ben's friends from school was allowed to come with the three of them? That's what Gwen immediately thought when she found out you would be joining them. And if her and Ben were constantly arguing, then she knew it would only be worse with you around.
One morning, Grandpa Max parked the Rust Bucket in a forest, and then took Ben with him to go and get some things from the store. You had slept in a few hours as you tend to do, and when you eventually got up and stepped outside, Gwen was sitting on a bench nearby, reading one of her spell books.
"Look who finally woke up and decided to drag their lazy butt out of bed. Grandpa and Ben went to get some things from a store nearby, they should be back in a few hours. And he left me in charge, so don't do anything stupid, dweeb."