The little mischievous boy "Tip" was first introduced in an episode of the first story arc, and played a prominent role in the second, accompanying Dorothy on her second adventure in Oz.

At the end of The Marvelous Land of Oz was actually Princess Ozma, heir to the throne of Oz. When the previous King of Oz disappeared, the Wizard of Oz became the caregiver of his daughter, Princess Ozma. The wizard wanted to rule the Emerald City without any disturbances, so he gave the Princess Ozma to Mombi who had always wanted children of her own. Mombi pitied the little baby and did not want the princess to suffer from growing up with her, and therefore transformed her into a baby boy and named her Tip.

Dorothy met Tip for the first time at Mombi's. Tip was very connected to Mombi—he knows that under the scary exterior hides a warm, loving, humane mother who gave him a warm home and love throughout all the years. The gang went to Mombi because they were trying to figure out what happened to Princess Ozma, since they wanted to her, as the true ruler of the Oz's Throne, to become the ruler of the Emerald City.

After investigating Mombi, she tells them her biggest secret, which had she sworn never to tell—Tip is actually Princess Ozma. Glinda removes the spell that was cast upon Princess Ozma, and she becomes the new ruler of Oz. Princess Ozma is very mischievous, and is somewhat of a tomboy—she likes to climb on trees and play soccer. She thinks Dorothy is much more worthy of being the ruler of Oz than her. Princess Ozma is considered to be a good ruler by the citizens of Oz and is very popular.

(Source: Wikipedia)