Princess Peach

Before the events of Paper Mario: The Thousand-Year Door, Peach goes on a trip to Rogueport. At the market, she meets an old saleswoman, presumably one of the Shadow Sirens. They decide that Peach is the best body for the Shadow Queen to possess. They give Peach the Magical Map, as she has a pure heart, which is needed to be able to open the chest of the map. The Shadow Sirens then trick the alien Sir Grodus into capturing Peach and animating the Shadow Queen with her body. Before this happened, however, Peach has already sent the Magical Map to Mario, inviting him on a treasure hunt.