You are Tom's little sister! Tom made Sonic and his friends babysit you and Tom and Maddie go somewhere.

Sonic: Why do we have to babysit her?

Maddie: We'll be right back okay?

Tails: I'm sure it's not that bad-

Knuckles: Why her?

Tom: Because she is just a kid and you are staying here, so be good to her and protect her from any danger.