Regina Fabia Sheen emerges as a Neathian royal, first appearing as the princess of Neathia amidst the conflict chronicled in *Bakugan: Gundalian Invaders*. Her core drive is defending her imperiled homeworld against the Gundalian onslaught, compelling her to seek allies on Earth for Neathia's survival. She wields considerable physical strength, evident when overpowering foes like Zenet Surrow or Dan Kuso during clashes. Her natural Neathian form features distinctive purple skin and large green eyes. Her human disguise presents navy blue hair partially obscuring one side of her face, green eyes, and unique attire: a white-and-orange robe with layered accents, rings, pink earrings, and white-and-blue boots. Upon ascending to queen in *Mechtanium Surge*, her wardrobe adopts regal robes reminiscent of those worn by her sister Serena. Fabia's past is marked by profound loss. She was engaged to Jin, the former commander of Neathia's Castle Knights, who fell in battle against the Gundalian agent Kazarina. Defying her sister's command, Fabia infiltrated Gundalia to rescue Jin's Bakugan partner, Aranaut, from Kazarina's experiments. These experiments erased Aranaut's memories of Jin, leading the Bakugan to believe Fabia had always been his partner. This tragedy fueled a deep-seated vengeance against Gundalians, shaping her initial distrust and hostility. Her character arc traces a journey from vengeance towards reconciliation. Initially distrustful of all Gundalians, she gradually extends trust to defectors like Ren Krawler, Nurzak, and others betrayed by Emperor Barodius. A pivotal moment occurs in "Forgiveness," where she challenges Ren to a brawl to test his loyalty. Confirming his sincerity, she accepts him into the Castle Knights, demonstrating her capacity for growth and forgiveness. She also shows empathy towards adversaries experiencing loss, like Lumagrowl after Kazarina's demise. Strategically, Fabia operates as a key battlefield leader. She integrates the human Battle Brawlers into Neathia's forces, appointing them as Castle Knights, and uses her knowledge of terrain for critical missions, such as reactivating planetary shields. Her tactical acumen shines in coordinated deceptions, like swapping Bakugan with allies to confuse opponents mid-battle. Following Neathia's victory in *Gundalian Invaders*, Serena abdicates and Fabia ascends as queen in *Mechtanium Surge*. This transition requires her to relinquish active brawling; she gifts Aranaut to Captain Elright, marking her shift from combatant to sovereign. Her responsibilities now prioritize diplomacy and governance, reflected in her role as Neathia's ambassador during interstellar engagements. Fabia's leadership balances resilience with compassion. She exhibits decisiveness in crises, such as evacuating civilians during Gundalian assaults, while fostering peace between former enemies. Her unwavering commitment to her people and planet defines her journey from princess to monarch.