Juvenile court erred when it established jurisdiction based on a factual and legal theory not alleged in the original petition. Mother, father, and the five-year-old minor G.B. were involved in a family court proceeding. The Department filed a dependency petition on G.B.’s behalf, alleging that the minor had been sexually abused by mother’s boyfriend, and that mother had failed to protect her from the abuse. Father was not named as an offending parent in the petition. Subsequently, the juvenile court found the petition not true, but on its own motion, added three allegations against father for emotional abuse of the minor because it believed that father had coached G.B. to lie about the abuse. Father objected to the court amending the petition on its own motion, and both the Department and G.B. opposed dependency jurisdiction based on father’s conduct. The juvenile court sustained one of the allegations against father, declared G.B. a dependent, and terminated dependency jurisdiction, with an exit order giving mother full custody of G.B. On appeal, father contended that the court erred when, after dismissing all the allegations in the petition, it added and adjudicated jurisdiction allegations based on a factual and legal basis not at issue in the original petition. The appellate court agreed and reversed, vacating the orders. The juvenile court should have dismissed the petition once it found that the allegations were unsubstantiated. It violated father’s due process right to a fair trial when it crafted, asserted, and adjudicated jurisdiction allegations based on a different factual and legal theory not at issue in the original petition. The juvenile court lacks the authority to, on its own motion, initiate dependency proceedings against a parent. Because the court improperly assumed the dual role of advocate and trier of fact, the court’s orders and findings as to father had to be reversed.